Treyarch intends for the Black Ops II campaign to branch and diverge depending on player actions. This could be something minor that changes a section of gameplay
Run down open street, you get shot by a sniper and die, turn to page 48 to respawn.
You enter the building, turn to page 32, you are ambushed by a small group, you are dead, turn to page 24 to respawn.
You run down the stairs, turn to page 57, as you pass under the bridge you are attacked by a raving hobo, he knocks you in the water and you drown, turn to page 84 to respawn.
You carefully make your way down the linear street, turn to page 90, you see a small patrol of generic terrorists up ahead, turn to page 96, you gun the terrorists down and proceed forward, turn to page 100, you have completed the mission.