IDC: Samsung and Apple are driving holiday sales by Philip Elmer-DeWitt @FortuneMagazine December 10, 2012, 3:46 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Source: IDC. Click to enlarge. FORTUNE — Once again, Samsung and Apple AAPL are the big winners in the quarterly Worldwide Connected Smart Device report that IDC released Monday. Combined shipments of PCs, tablets and smartphones grew a healthy 27.1% year over year in the third quarter of 2012 according to IDC — a total of 303.6 million devices worth $140.4 billion. But the growth was heavily weighted to the markets where Samsung and Apple dominate: smartphones and tablets. IDC expects more of the same this holiday season: tablet shipments in Q4 are expected to grow 55.8% and smartphones 39.5%, while PC shipments are expected to decline slightly from this quarter a year ago. In a set of stats that neatly sums up the competition between the two companies, IDC reports that Samsung maintained the top position in market share (21.8%) based on shipments, while Apple, which ranked second in shipments, led all vendors in the value of products shipped ($34.1 billion). “The battle between Samsung and Apple at the top of the smart connected device space is stronger than ever,” says IDC’s Ryan Reith. “Both vendors compete at the top of the tablet and smartphone markets. However, the difference in their collective ASPs [average selling price] is a telling sign of different market approaches. The fact that Apple’s ASP is $310 higher than Samsung’s with just over 20 million fewer shipments in the quarter speaks volumes about the premium product line that Apple sells.” The chart above shows IDC’s forecasts for the next four years. Below: IDC’s spreadsheets.