So in Assassins Creed III just like pretty much any other game out there you can dress your character up in some sort of special attire that is different than the default. Assassins Creed 3 is no different, Connor has a total of 12 outfits that he can wear that can be achieved or purchased throughout the game. Now these outfits don’t actually give Connor any special abilities added strength/defense or features other then looking kick ass when killing people.
Six of the 12 (actually 11 since you get the default outfit when you start the game) are purchasable outfits/skins as you finish sequences and four more outfits are achievements with the final outfit being only available with uplay. Check out the table below to see the entire list of outfits available.
Bottom line, Outfits don’t really do anything in terms of game play or special ability but they are fun to collect and make Conner look even more kick ass when killing and assassinating people.