Odd, I thought it was AF3. Just going off of XI:

AF1: Quest gear. Upgradable to +1.
AF2: Dynamis drops.
AF3: Empyeran gear. Upgradable to +2.

As an example, AF1 for DRG was "Drachen" gear. AF2 was "Wyrm". Both sets exist in XIV, completely independent of each other.