This thread again?ok.
This happens mainly because there is more variety in Sony exclusives.There are loads of exlusives for pretty much every genre.Because of that,PS3's userbase rarely gives attention to one particular genre(FPS-COD),while on the 360's side it happens more often with gears of war,halo,COD games,making the console king of the FPS games.
And there's America.Games usually sale more in NA,and the 360 has a pretty huge lead over there.







