in mw3 there are new operators, new weapons, new wz and multiplayer maps, new campaign and a new open world zombie mode
there are 16 new maps all from the 2009 mw2
The map names : Rust, Favela, Sub Base, Highrise, Estate, Karachi, Afghan, Derail, Invasion, Rundown, Quarry, Scrapyard, Skidrow, Terminal, Underpass and Wasteland
the warzone map called as Urzikstan
There are 37 new guns in mw3
Assault rifles : SVA 545, MTZ-556, Holger 556, MCW, OG-58 and FR 5.56
Battle rifles : Bas-b, MTZ-762, Sidewinder
Submachine gun : Striker, Striker 9, WSP-9, WSP Swarm, AMR9, Rival-9
Light machine guns : Bruen Mk9, Holger 26, OG-58 LSW, Pulemyot 76 and TAQ Eradicator
Sniper Rifles : KATT-AMR, KV Inhibitor, and Longbow
Marksman Rifles : DM56, KVD Enforcer, MCW 6.8, and MTZ Interceptor
Shotguns : Haymaker, Riveter, and Lockwood 680
Pistols : COR-45, Renetti, TYR, and WSP Stinger
Melees : Karambit and Gutter knife
Rocket Launcher : RGL-80