User blog comment:KATANAGOD/Treyarch Teases Zombies on Facebook/@comment-4312627-20120914015522/@comment-1263839-20120914164410

I would compare MW3 to more of an expansion pack to MW2 than a map pack. Map Packs generally don't include Campaign, Spec Ops, Dozens of Maps, and Multiplayer.

It's campaign follows the same theme (playing as morale lacking British men chasing down some Russian while you also play as a team of Americans with an annoying leader screeching "'muricah, fuck yeah!" down Russian earholes and killing millions of Russians along the way). It's multiplayer is near-identical with some revamping. It's Co-Op is given an update, with a new mode within it. These are all typically found in expansion packs. But overhyped... most definetly.