The Terminator T-600 is a new version and much upgraded Terminator robot, a perfect match to Christian Bale's character as John Connor. I think there's a reason why they have an upgraded Terminator and it maybe a result of the change of the grim future after all those failed attempts to kill John Connor, thats why we didn't saw this T-600 in the past movies. Maybe they realized to upgrade more and be deadly than the previous models. I'm not sure if this is the road to T-800 or T-1000.
more pics below
thanks to SHH for sharing the pics