When is a tablet not a tablet? When it's a PC. According to UK-based research firm Canalys, tablets are PCs by another name, or even in sheep's clothing.
The argument isn't just semantics. If the number of iPads Apple sold in the fourth quarter of 2010 is added to the number of Macs sold during the same period, Apple vaults onto the Top 5 list of the world's biggest computer makers.
In fact, iPad sales pushed Apple to the No. 3 spot, said Canalys, with 11.5 million machines, or 10.8% of the global market. Only Hewlett-Packard, which sold 18.7 million systems, and Acer, with sales of 13.6 million PCs, led Apple last quarter.
According to Apple's latest earnings report, it sold 7.33 million iPads and 4.13 million Macs, both records, for a total of 11.46 million.
Tim Coulling, a Canalys analyst, argued for putting the iPad in the PC category, while a colleague criticised anyone who disagreed as "out of sync."
"It all has to do with how the tablet product is used," said Coulling. "It's a multi-use product that carries out such functions as word processing, email and the Internet."
To back up his argument, Coulling said tablets were analogous to netbooks, and said that the same debate, "Is it a PC?", raged several years ago. "It's the same thing we saw with netbooks," he said. "People said, 'This isn't a PC, we can't do everything we want to, we can't burn a DVD, it doesn't have a fast processor.
"But when new products come along, attitudes have to change," Coulling said. "You have to look at what new developments are taking place in the market."
Other research companies, however, disagree. Neither of the biggest US research companies, Gartner and IDC, count tablets as PCs when they estimate sales numbers.
"We see PCs as devices meant to run a general purpose operating system that allows content creation as well as content consumption," said Jay Chou, an analyst at IDC.
Apple's iPad runs iOS, the same mobile operating system that powers the iPhone smartphone. The two also share the App Store, Apple's software marketplace, and the iPad can even run iPhone applications.
"For now, we're not counting tablets as PCs, even though they are cannibalising PC sales to some extent," added Chou. "But that's not set in stone."