What is the difference between Kingdom Hearts Chain of Memories and Kingdom Hearts RE Chain of Memories?

Kingdom Hearts Chain of Memories was released for the Gameboy Advance in 2004 (Japan), as a sequel to Kingdom Hearts. Three years later, in 2007, a remake of the title was released for the PS2, alongside the Final Mix+ version of Kingdom Hearts II (Japan).

Kingdom Hearts RE: Chain of Memories is a 3D rendition of the original title, with full recreated cutscenes, including voice-acting and additional scenes not seen in the GBA title. The PS2 remake also allowed for more of a visual fighting system. More vibrant attacks, and added abilities were some of the many minor tweaks to the game. Kingdom Hearts RE: Chain of Memories also included an extended, alternate version of the Final Boss battle against Marluxia.

Overall, the game is essentially the same. The graphics/look of the game is the only major difference. You will get the same story on either the GBA or the PS2.