The Nikon has more verticle & horizontal adjustment than Weaver. I have both and as was stated, the Weaver is a litlle sharper, although not by much, but the knob adjustment and setting is not the best. Nikon comes with two set of knobs (target & hunting) and has 50 MOA (minute of angle) where the Weaver only has (I believe)36 MOA.
Good Luck & Good Shooting,
Gary