Similar offensive players, maybe slight edge to buckner. Ivey's a better passer, but not near the defender IMO.
I actually think Ivey's one of those guys who people go "he's not an offensive player, so he must be a defensive stopper", when that's not really the case IMO. He gives effort defensively, but overall I think he's actually a mediocre defender. At least, that's the impression I've gathered from what little I saw him, combined with his defensive PER, and talking to some bucks fans I know.