While previous Call of Duty games on the PlayStation 3 and Xbox 360 have supported 9v9 matches, Call of Duty: Ghosts seems set to only allow for 6v6 across the current generation platforms. In addition, Ghosts is going to require 3GB of hard drive space to install its single player campaign, which is optional, but if you've got a 4GB Xbox 360, you might want to get a flash drive ready.
The apparent reduction in player count comes courtesy of the back of the game's PlayStation 3 and Xbox 360 boxes, as well as Xbox.com. If true, it seems a surprising move, what with the general trend being higher player counts, rather than smaller. Having said that, I'm reasonably certain 6v6 has always been the more popular Call of Duty size on consoles.
The install size comes courtesy of Activision's Community Manager Dan Amrich, who also revealed that the pre-order DLC map Freefall with require another 250mb of hard drive space.