LOL both games are for multiple players, Borderlands is a FPS with RPG elements so if you can't keep up with numbers and upgrading stay away.
L4D2 is dope too, its not the same exact shit as the last one, new maps, new weapons but same game play if that's what you're talking about as the same exact shit.
There both fun games I own them both, If you have Xbox Live you can always join a group playing both these games.