both quotes from fourzerotwo
"Both versions, Xbox 360 and PS3 have the same number of players.
They both have 16 players max, except on Ground War gametype which has 18 players max. On BOTH consoles.
This applies to RANKED games on both consoles. Keep in mind you can have 18 players in private matches on any gametype on both consoles."
"Ground War is a specific 18 player playlists in Multiplayer. Essentially, it's exactly what it sounds like. Lots of people, lots of death. I'll let you experience it for yourself in a week."