Guilty Gear Xrd REV 2 is the final revision of Guilty Gear Xrd, released initially as a major title update for Guilty Gear Xrd -REVELATOR- in arcades, and then later released as both an expansion for previous owners of Guilty Gear Xrd -REVELATOR- on PS3, PS4 and Steam or as a standalone title on PS3 and PS4.
REV 2 features a short list of system changes, two new characters -
Answer and 
Baiken - significant changes to the game's visuals and camera, a complete rebalance of the cast, expanded story content, and new stages. REV 2 also received an additional rebalance in Ver.2.10 which introduced further changes to the cast.