Black Ops Through the Ages
I and II and III
Black Ops II Multiplayer
The biggest new feature in Black Ops II is the pick 10 class system which allows players to have 10 allocation slots for perks and attachment etc. Whats also new is guns have experience now so you can level up a gun to get attachments for it, they can also prestige the gun and put clan tags and emblems on it for exchanging all the experience it had on it before. The one thing that was added that wasn't in any other game was the league play mode.
Black Ops III Mulitplayer
There are different moving based things added too, like a jet pack which boosts players into the air. There is wall running and sliding too. In addition to the pick 10 classes form Black Ops II, there are now specialists. Players can pick form 9 different people who have different abilities and special weapons.
Official Call of Duty®: Black Ops III Reveal Trailer