I believe that Activision is the publisher for ALL Call of Duty games, at least from CoD4 on.
There are two developers, actual designers of the game, which both produce a game bi-annually, on an offset cycle so we have a new COD every year are Treyarch and Infinity Ward.
Infinity Ward - CoD 4, MW2, MW3 and now Ghosts
Treyarch - World at War, Black Ops, Black Ops 2
It's generally agreed, that Infinity ward definitely makes the better Call of Duty games. However, I wasn't a huge fan of MW3, and never bought black ops 2.