Sonic’s Ring

MW2 is quicker, more reaction based and less of a time sink. It requires little forward planning and you just make it up as you go along. Games are over in minutes. Maps are smaller. And major difference is no team work. Even when I play with my clan, it's you fighting for yourself.

BFBC2 is slower and more thought based. Team work is essential as games can last from 15 minutes to an hour. The game-play elements are deeper with you have to consider distance when taking longer range shots, having to make sure your cover isn't too obvious when holding bases, deciding on which vehicle to use and navigating destructible environments. As well as the class system and getting into squads.

4 Classes, Each has a specific trait. Like a medic can revive and dish out health, which is essential to winning games where your team has a set number of "new" spawns.

Maps are also sometimes 10/15 times the size of what they are MW2 with more players in each map and to my experience little to no lag overall.

I honestly prefer Killzone 2 over both of them. As it's even more of a thinkers FPS online with full clan system, 32 players, more classes and such. But less of that.

That picture from E3 wasn't representative of the genre. You could get a small screen grab of the behind the car view of Split/Second, Gran Turismo 5 and the new Need for Speed and they'd all look very similar... But to say they were anything like each other past that you race would be a fools statement. All play differently and appeal to different players.