Considering I think Cameron's best work is T1 and the rest of his filmography is a slide down from that point, it's pretty easy to deduce what Tarantino is better than Cameron at.
Experimentation within a frame, varying pacing, complex framing, use of palettes within the frame, emphasis on conservative cutting, a bunch of things Tarantino does that set him apart from a great many directors working today.
Cameron is a serviceable director that has an eye for what stories will work for him and he doesn't get in his own way when creating what he wants. That's about it.