"There are major gameplay balance differences between the two. Weapons feel different, with different fire rates and recoil. And the damage model has been radically shifted. Death comes quickly in the beta, situated more towards Call of Duty's durability, or even last year's DICE-developed Medal of Honor multiplayer. Firefights in the beta prioritize reflexes over tactics, which is a departure from Bad Company 2.
This is not the case with Battlefield 3 as it is now. The version of Battlefield 3 that I spent hours playing last week has weapons and damage that feel like Battlefield Bad Company 2. This, if you aren't sure, is a good thing. It changes the dynamics of firefights, allowing for each side to take and hold positions, and making flanking and tactical coordination much more viable. The increased player survivability also make vehicles in Battlefield 3 more fair than they would be with the beta's damage models."
http://www.joystiq.com/2011/10/10/th...battlefield-3/