You iPhone. Me iPod touch.

What — besides a two-year, $2,000-plus commitment to AT&T (T) — makes a person who carries an iPhone different from one who’s got an iPod touch?

From January to May, comScore tapped into AdMob’s U.S. advertising network to conduct a survey of owners of both Apple (AAPL) mobile devices and drew some interesting conclusions, which it released Tuesday morning.

First, the comScore/AdMob survey, like last week’s Forrester report, identified several ways both groups differ from the general population. For example,

70% are men
Half use the mobile Web more than they read newspapers or magazines
More than 40% use their mobile devices more often than their computers to visit the Internet
More than 40% spend more time on the mobile Web than they do listening to the radio

But when the researchers drilled into their data, they discovered that iPhone and iPod touch owners occupy very different demographics. For example …

iPhone owners are older. 69% of iPod touch users are between ages 13-24, while 74% of iPhone users are older than 25
iPod touch owners are less wealthy. 78% of iPhone users have a household income of $25,000 or more, compared with 66% of iPod touch users
iPhone owners have more kids. 46% of iPhone users have children while only 28% of iPod touch users do
iPod touch owners are more likely … to be in the market for cellphones, clothes, TVs and other electronics
iPhone owners are more likely … to spend money on travel, financial services and a new home

Most of these findings flow directly from the first: iPhone owners are older and therefor have more money, more kids, more need of financial services, etc. (The one thing most don’t need is another cellphone.)

And you might think that this age difference flows directly from all those free iPod touches Apple handed out last summer — and will hand out again this summer — to college students buying MacBooks.

But Jason Spero, AdMob’s North American managing director, thinks it has more to do with 1) the cost of that two-year commitment to AT&T, and 2) the big advertising campaign Apple ran last December pushing the touch — and the explosion of games that run on it — as the “funnest iPod ever,” a campaign clearly pitched to younger users.

Spero says the effect of Apple’s marketing push leaped out of their December data: an explosive, almost vertical spike in AdMob’s iPod touch Web requests between Dec. 24 and Dec. 25. “The iPod touch became THE gift for Christmas,” he says.

ComScore describes itself as a leader in measuring the digital world, and AdMob is the world’s largest purveyor of mobile Web ads. ComScore used invitation banners to solicit respondents from AdMob’s network and ended up interviewing 3,454 iPhone users and 3,848 iPod touch owners.