In looking through all the pictures on Anet of A320s and -321s, etc, what exactly is the difference between the models? I've seen A320-211s, -212s, -214s, -231s, -232s, and that sort of thing. Is it an engine difference (I've noticed the -231s/-232s all seem to have IAE engines)?
This question has been kind of bugging me, so if you know, I'd appreciate it! Thanks in advance.