Check the video I posted just below your post. That would have been his 3rd penalty giveaway already this season (although 1 would have been undeserved) and a stupid grabby foul in a similar position as Aurier's against westham.Both are equally poor defensively, I would say neither are great at crossing the ball, both are out of position too often.
But Doherty does not have the dumb mistakes that Aurier does, does not turn off like Aurier does and is much better at getting involved in the play around the opposition box.
Its not much but it is a clear upgrade.