Modern Warfare 3's multiplayer has been overhauled to offer three differing proficiencies, as explained in the "Strike Packages" trailer.
Capturing marked objectives and outgunning opponents still forms the basis of Modern Warfare 3 multiplayer, unlocking immediate benefits that relate to each role.
The Assault package grants access to enhanced missile strikes, automated sentry guns and assault drones.
Those selecting a Support role find that their pointstreaks are not reset when an enemy gets the better of them, making it easier to upgrade equipment that assists teammates.
The Specialist's role sticks stubbornly to the traditional killstreak system. Each consecutive kill unlocks an additional character perk, turning them into super-soldiers if they can stay alive for long enough.
The move to a pointstreak system can be seen as a nod to other first person shooters such as Team Fortress 2 and the Battlefield series.
Coincidentally, Battlefield 3's recent public beta map Operation Metro was perhaps most similar to a Call of Duty set-up, lacking the sort of vehicular combat typical of a Battlefield title.