If you look at the actual in-game stats, the damage is almost exactly the same. The AK is slightly more accurate though, so I guess it is technically a better weapon.
the in game stats are just for show really, its all in the programming. an ak to the chest will put someone down in a bullet, a tar wont necessarily do that.
a guy i used to play with with drake would sit on any forum he could to find official damage/health stats for each gun would find shit the programmers would post to answer questions.