Originally Posted by Bagge
Sales are probably quite a lot lower than the number of people on the leaderboards. Several different people with different accounts can play the same downloaded game on the same xbox and have individual rankings on a leaderboard. There are probably a lot of siblings and friends who are ranked on the leaderboards without having bought the games.
That's not true, games are linked to account AND console on 360, or at least I couldn't play games on my friend's 360 with an account I made, haven't ever made a secondary account on mine though.