What spyder said is right..
MW2:
-Glitchers
-Prestige hackers up the ass
-Noob tubers up the ass
-campers like mad
-Little kids talking trash in lobbies thinking there cool
-Takes nothing to level.. just kill and lvl
-Small boring maps
-Cant demolish buildings
BFBC2:
-Large Maps
-Tanks/Helicopters/Driveable UAVs/ETC
- Small bit of campers but who cares
-Leveling system is different.. you have to work for your rank.. not just kill people
-No rank glitchers
- Less noob tubing
-Can blow things up
IMO I like BCBF2 better.. your freely able to go where ever you want.. on a nice large map.. you can demolish houses.. drive vechiles.. need to work for your ranks.. I'd rather choose this game over MW2 anyday because of the stupid bs in the game. From the glitchers, to the noob tubers, to the nuke boosting etc.. BF FTW