User blog comment:N7/Battlefield 3 Beta is an older build of the game + Changes from Beta to Final game/@comment-189.141.213.113-20111003091844/@comment-3453223-20111003204416

So DICE could get community feedback on issues such as glitches, bug, weapon balances, etc. before the game even came out so it could be fixed by the time Battlefield 3 was released.