Offensively, Hill shoots the 3 better, finishes on full court fast breaks better, is always unselfish when it comes to giving the ball up, but lacks the leadership and experience of Parker. Isn't as talented at at getting good open looks in the halfcourt which is one of Parker's strongest skills. Hill also looks to be 100X more durable than Parker so far in his career.
Overall I'd say they are very close, w/ Parker and his experience giving him the edge right now, but its much closer than the TP fanboys want to admit.