Better tier troops and equipment will cost more points so players have to be strategic about how they spend them.
One side besieges a castle while the other team defends. Current Mount & Blade II: Bannerlord Multiplayer Game Modes There have been some rumors of a possible future DLC providing some sort of CO-OP campaign mode but with how the single-player sandbox campaign works it doesn’t seem likely.
While Bannerlord does feature multiplayer gameplay, at the moment you are not able to play through the regular campaign with your friends.