FORTUNE — When you consider the greatest business minds of the past 100 years, certainly Steve Jobs and Sam Walton have to be at the very top of the list. Jobs created the most valuable company on earth (though down from an all-time high, Apple (AAPL) is still worth more than $500 billion), while Walton founded and built Wal-Mart (WMT), the biggest company in the world, with more than $450 billion in sales over the past 12 months. But Jobs and Walton did even more than that. Both created retailing, business, and even societal revolutions. They changed the way we buy, shop, and interact, and even how and where we work and live. The two men were vastly different. Jobs was a business version of a California counterculture icon. Walton was an old-school heartland conservative. And yet they were remarkably similar too: iconoclasts, of course, relentless, and often very tough on the people around them. And that’s just for starters. If you really drill down into their lives and careers, all kinds of really cool insights emerge.
Who better to compare and contrast these two remarkable men than their remarkable biographers, Walter Isaacson and John Huey? Isaacson, author of Steve Jobs, is the CEO of the Aspen Institute, a former head of CNN and editor of Time, and also the author of biographies of Kissinger, Franklin, and Einstein. Huey, who wrote Sam Walton: Made in America with Walton, is the editor-in-chief of Time Inc., the former editor of Fortune, and my boss.
The inspiration for this conversation came from an interview of Huey and Isaacson that I conducted in early September at the Global Summit for the Closely Held, put on by BDT & Co., a merchant bank for family-controlled companies headed by Byron Trott, who founded the company three years ago after leaving Goldman Sachs, where he was famously Warren Buffett’s banker. Huey and Isaacson had plenty to say about their subjects. (As you can see, I didn’t really have to ask many questions!) What follows are the highlights.
Andy Serwer: These books are must-reads for students and practitioners of business — there’s no doubt about that. Sam Walton and Steve Jobs are two of the greatest business leaders in history. So I want to start by asking our biographers: How did you get to know the subjects of your books?
Walter Isaacson: I’d known Steve Jobs since 1984, January, when I was at Time magazine, a junior writer, and he came to show off the original Macintosh. I saw both sides of his personality. He had us use a jeweler’s loupe to look at the cool icons. Then all of a sudden he turned dark and started berating us, saying we would never get the beauty of this sort of thing. I saw the intensity of his personality, and I came away liking him.
When I became editor of Time, and then at CNN, he was my good friend for two days a year when he had a new product out. So there was that relationship.
I got a phone call when I went to the Aspen Institute in 2004. He said he wanted to take a walk. I said, “Sure.” I didn’t know that taking a walk was the way he had meetings. I’d written a book about Benjamin Franklin. I was just finishing up a biography of Albert Einstein. He said, “I want you to do my biography next.” My initial reaction was “Yeah, okay, Ben Franklin, Albert Einstein, you …” I wondered, half-jokingly, whether he saw himself as the natural successor in that sequence. I said, “Maybe in 20 or so years, when you retire.”
Later his wife said to me, “If you’re going to do a book on Steve, you had better do it now.” By then it had become public that he was sick. She said, “He didn’t want people to know, but he called you right before he was operated on for cancer.”
Serwer: John, what about you with Sam Walton? How did you guys get acquainted?
John Huey: I went to work for Fortune in November of 1988, and they decided they wanted to make Wal-Mart the “most admired company.” Usually when you call up a company and say, “We’re going to make your company the ‘most admired company’ on the cover of Fortune,” they roll out everything. Wal-Mart said, “Not interested. We don’t want anything to do with it.”
And the editor said, “We have to have cooperation,” because there’s never been a posed photograph of Sam Walton. He’s avoided the press. The editor said, “You’re a Southerner — you go down to Arkansas and talk him into it.”
I went down there. It was two weeks before Christmas. It was horrible weather. I went over to Wal-Mart, and I just basically knocked on the door. His assistant — her name was Becky — said, “He’s hunting. He’s not available.”
This went on for days. Rain kept on going. I knew that he drove this old pickup truck. So I kept riding by there looking for the pickup truck.
Ten days into this I said to my photographer, “We’re going to go back over there, and if we don’t see that truck, we’re getting out of here.”
So we rode by, and there was the truck. Sam Walton was in the building. We went in, and I picked up the vendor phone and said, “May I speak to Becky?” Sam answered the phone. I said, “Is this Sam Walton?” He said, “Yes.” I said, “Well, this is John Huey from Fortune magazine. I’ve been here 10 days. It’s raining. My wife is going to leave me, and if I don’t get this picture, they’re going to fire me and I’m going to have a terrible Christmas, and all I need is 10 minutes.”
You know, journalists have no pride.
He came out, and we took the picture. He complained the whole time. “You’re wasting a lot of flashbulbs, you’re wasting a lot of the film.” And then he said, “Oh, and by the way, you can’t put this picture on the cover.”
We negotiated. We got the cover. I wrote a long story about Wal-Mart, and then over the next three years or so, I was flying in planes with him and driving around and basically hitchhiking across America.
Serwer: Let’s talk a little bit about the men themselves, Steve Jobs and Sam Walton, and how they’re the same and how they’re different.
Isaacson: I think I understood everything about Jobs except for why he opened up so much. It was exactly a year ago this week when I went to Palo Alto for the last time. I kept asking him, “Why did you do this? Why did you do this?” And he said, “I have an amazing life. It was very interesting. I just think people ought to know.”
Huey: Sam was very different from Steve in a lot of ways, but they had some similarities. They were both showmen. They both loved to hold court on a stage and mesmerize people. They were both extreme charismatics. They were obsessed with competition.
Sam was not a reflective person. Writing a book that was his story was difficult because he didn’t really care about that. He didn’t really remember it. And I had to shore it up. I had to do reporting for him to do his own story because he couldn’t remember what year anything was. He was always looking ahead.
Steve really saw himself as a philosopher and an intellectual. Sam was a throwback. He was a throwback to Andy Hardy and Horatio Alger. He would hire donkeys and put them in the front of his stores to open them. He would have Ferris wheels in the parking lot.
Isaacson: Steve knew how to open a store too, and he was a showman too. But there was a basic and fundamental distinction. Steve was focused on product and did not focus mainly on profit. He said, “If you keep your eye on the profit, you’re going to skimp on the product. But if you focus on making really great products, then the profits will follow.” He was motivated by making the most beautiful products he could imagine. He never wanted to compete on price or be a commodity.
Huey: Steve was focusing on an elite group of people who appreciated the art of his business talent. In so doing, he focused on the product, and he created a product that had margins that were as insanely great as the insanely great products. Sam was the exact opposite. He focused on being able to open a store in five days, and if the margins got above anything that was infinitesimal, he was angry. He was a businessman who had to keep margins down because he was all about volume. He wanted a clean store, but he wouldn’t spend a penny on design. For years they did their own ads with clip-art books. Steve would design a new font to have an ad.
Isaacson: For his store he took out a design patent on that staircase, and his name is on that patent, and most of the major Apple Stores now have them. He said, “You want that stairway so people believe they’re in someplace magical.”
Huey: Sam would take his executives around to the worst store that he could come up with, and he would say, “This is a horrible store. I want everybody to come out of there with one thing they do better than we do because everybody does something good. And there’s something in there that we could do.”
Isaacson: When Steve took his people on a tour, he took them to the Tiffany Museum because he wanted them to see that you could do awesome design like Louis Comfort Tiffany did but also have it be so people could have it.
Huey: Even in Sam’s earliest days as a 10-cent-store owner, he would never sell a Hula-Hoop because a Hula-Hoop was branded and came from Wham-O, and you’d have to pay Wham-O something for having developed the product. Sam looked at it and said, “It’s a round piece of circular plastic. Get somebody to make us a round piece of circular plastic, and we’ll call it something else and we’ll sell it for half the price!”
Isaacson: That’s what Samsung did with the Apple iPhone, and they got sued.
Huey: There are so many exact opposites, and there are so many parallels. Sam had multiple myeloma. And he, like Steve, sought out all kinds of exotic cures. Brought people in from Germany.
Isaacson: Both of them did not believe that the normal rules applied.
Huey: To anything.
Isaacson: To anything. For Steve and I think for Mr. Walton, it probably worked 90% of the time.
Huey: My two favorite Sam Walton breaking-the-rules stories: One time we’re flying, and the air traffic controller comes on the radio and says, “You’re in unauthorized air space.” Got the tail number and all. And Sam just turns off the radio. We keep flying, he’s got his spreadsheets taped to his leg, and we’re looking for a store — he’s looking for the worst-performing store because that’s where we’re going to land. And we’re flying, and the radar’s there, and it’s green and it’s yellow and it’s red, and I’m like, “Sam, why are we flying to the red?” and he said, “Because that’s the quickest way.” I said, “That’s like a tornado.” He said, “It’s the quickest way.”
The other story was when he was in the hospital in Little Rock. He was dying, and his family had gone out for the day to go shopping and left me there. He says, “John, I want to get out of here,” and he starts pulling the tubes out of his arm. I said, “We can’t leave.” And he said, “I’m going. Are you going with me?” And he picks up the phone and he calls the Bentonville airport — his airport — and he says, “Send a plane down here. I’m going to be there in 45 minutes.” And I have to pull him out of the bed. I roll him out, down into the lobby. He’s a shrunken little old guy, and he gets down to the lobby and says, “How are we going to get to the airport?”
I said, “Yeah, you didn’t think of that, did you?”
Isaacson: When Steve was in the hospital in Memphis after the liver transplant, they had to put an oxygen mask on him, and he keeps pulling it off and saying, “This design sucks.” He asked them to bring him five different options so he could pick a design he liked. It was the same type of thing he would do at the Apple design studio.
Huey: I mean these guys —
Isaacson: Didn’t live by the rules. But sometimes they’re right. At one point Steve wants to do the iPhone, but he doesn’t want the face to be plastic. He wanted it to be this beautiful silky glass. Steve being Steve, he just picks up the phone and calls the Corning Glass (GLW) switchboard and says, “Let me speak to your CEO.” The switchboard says, “Fine, we’ll take your name and number.” He says, “Typical East Coast bullshit,” and slams down the phone.
Wendell Weeks, the Corning CEO, is a cool guy. He hears about it, and he picks up the phone, calls the switchboard at Cupertino, and says, “Let me speak to your CEO.” They say, “Will you fax your request in writing?” It gets back to Steve, and Steve says, “I like this guy.”
They have a meeting, and Steve says, “I want this type of glass.” Weeks says, “Well, we once did a process called Gorilla Glass that has this ion transfer. It’d be kind of good, but we never made it.”
And Steve looked at the process, said, “Yeah, that’s what I want. I want this much by September, and do it secretly.”
And Wendell says, “Well, I just told you, we’ve never made it before. We don’t have the capacity.” And Steve just stares at him, unblinking, and says, “Don’t be afraid. You can do it.” And they did. He had what they called a “reality distortion field,” and it compelled people to do amazing things that they thought were impossible.
Huey: Right, and that’s the glass that’s on your iPad.
Serwer: And that’s a huge business.
Huey: Sam Walton completely transformed the distribution business worldwide because he couldn’t get anybody to distribute to him. He was constantly looking at his numbers. He realized a really important fact, and he asked the CEO of Procter & Gamble (PG) to come to Bentonville, and the guy said, “Well, you know — ”
He said, “I think you’d better come to Bentonville. I have some really important business to discuss with you.”
So the guy came to Bentonville for the first time ever, and Sam said, “I’ve discovered something that I think you and I need to know before we go any further forward.”
And the guy says, “What’s that?”
And he said, “Wal-Mart accounts for more of your business than the entire country of Japan, and you don’t even have anybody who will call on me in Bentonville, much less be based here. Everything’s going to change. You’re going to open an office here. You’re going to treat us like we’re Japan.”
And he pretty much did that to the rest of the world, and as a result, he ended up taking all the pricing power away from the manufacturers.
I would say they were both some of the most difficult people in the history of the world to negotiate with because their idea of a negotiation was, if you said no, they didn’t hear it.
Serwer: Wal-Mart has been wildly successful since Sam’s death. At Apple, Tim Cook took over a year ago, and now the company’s market capitalization is $270 billion bigger, and the question everyone asks is, “What’s going to happen at Apple?” This is a pretty good template, right?
Isaacson: Apple’s future as a company was one of the things that a year ago Steve was obsessed about. He had gone in at the end of August to tell the board that he was stepping down as CEO. And everybody on the board is very sad, and then they try to jolly things up, and they talk about how Hewlett-Packard (HPQ) had just gotten out of the tablet business that day, was screwing things up, and he said something like, “Wait a minute. Bill Hewlett gave me my first job. When I was 13 years old and needed a part, I called him from the phone book, and he gave me a summer job, and he and David Packard thought they’d made a company that was going to outlast them and continue to grow for a generation, and these bozos have screwed it up. Don’t let that happen to Apple.”
He said, “Here’s what’s in our DNA at Apple. We stand at the intersection of art and science; at the intersection of creativity and technology.” And he said, “That’s been in the DNA of great companies. That’s why Walt Disney (DIS) — even though people tried to screw up that company — it’s still going to survive.”
Huey: One of the last conversations I had with Sam, he was lying on his hospital bed in his living room and he was weak, and he was down to skin and bones, and he said, “John, I don’t know. We built a heck of a company over there. But I can just tell. I haven’t been over there in a month. I know they’re over there screwing it up.”
Serwer: Who was the greater genius, Sam Walton or Steve Jobs?
Huey: Genius? Steve Jobs.
Isaacson: “Genius” is a word thrown around pretty loosely and shouldn’t be, but if it applies to anybody, it applies to Steve Jobs. He actually wasn’t the smartest person in the digital revolution. Bill Gates had more conventional mental-processing power than Steve did in terms of analyzing information and data. But Steve Jobs had an intuitive genius, and that genius comes not just from being smart but from being imaginative and creative. And making leaps that come from thinking differently.
Huey: Steve was like Edison. Edison was a genius. We don’t know what his IQ was, but it may not have been very high. We don’t even know if — we don’t even know that Steve could do math.
Sam was more like Henry Ford. He was very focused on changing something that was massive and structural. Was Henry Ford a genius? I don’t think so, but he was a great businessman. Sam Walton was a great businessman. Walter made a joke about Ben Franklin and Einstein and Steve Jobs, but I don’t really think it’s a joke. I think they were all geniuses.
This story is from the December 3, 2012 issue of Fortune.