Yeah, completely different players.
They are both undersized (though JJ extemely) players who rely on speed; their best offensive is attacking the rim, both hustle players. Obviously due to JJ's size he's going to have more trouble rebound, defending, and passing.
I see JJ as a very poor man's Rondo. But the main point is Rondo will never be dominant and elite (like many expect him to be) unless he can shoot. All teams are going to start crowding him in the paint and he becomes a liability on the offensive end of the floor.
For those who watched most of the playoff games, LAL OKC MIA all had trouble guarding JJ because they had to respect his outside shot, and then he burned them going to the rim.