Well you've probably already heard about the new armor mods or perks which come from selecting a certain specialization.
There are currently around 8 specializations for Halo 4 that will grace your consoles this fall. But not having time to understand them fully, here is a link to IGN who breakdown very nicely and simply each specialization for you all to come to grips with.
Also only 2 of these specializations can be chosen from the moment you first start playing, a for the otheres the intention is really to extend the replayability and long life of Halo 4's multiplayer, whilst allowing you to try out different styles of play later on.
http://uk.ign.com/articles/2012/08/15/halo-4-specializations
There are currently around 8 specializations for Halo 4 that will grace your consoles this fall. But not having time to understand them fully, here is a link to IGN who breakdown very nicely and simply each specialization for you all to come to grips with.
Also only 2 of these specializations can be chosen from the moment you first start playing, a for the otheres the intention is really to extend the replayability and long life of Halo 4's multiplayer, whilst allowing you to try out different styles of play later on.
http://uk.ign.com/articles/2012/08/15/halo-4-specializations