No but not by much. Fox is older and more polished but less dynamic. When people say dynamic, they're really referring to how many ways a guy can beat you and the unpredictability in their game (why so-called "dynamic" players have spotty defense mostly). I still see Smith as calibrating defensively, especially trying to figure out how to physically contain bigger forwards in the corners. But most of the time, he and Severson are controlling the game when they're on the ice. Been mutually beneficial.
That being said, while I'm thrilled with Smith, he could learn some things from Fox, mainly just simplifying in high stress portions of the game. It's not like he's some wildcard but as a whole, the NJ team sometimes leans too much on skill to get out of a jam when you really want to see the young players diagnose a high risk situation and be content to get out of it first, before attempting creativity. A fine line there.
Fox is fantastic and would rate him ahead of a lot of players, though.