The biggest difference is the two ring version has a tripod foot and the one ring or push pull version does not. Both lenses are optically excellent with a very slight edge going to the two ring version. The AF gear drive in the one ring is slightly slower than in the two ring version as well, though, the torque of the AF motor and AF module in the body is the ultimate limiting factor with regard to AF speed. Given a high end body, the focus speed should be fast enough for most subjects. Good Luck and Enjoy your Nikons!