What is the difference between ARM64 and Rosetta?

Rosetta is a software that allows Baldur’s Gate 3 to run on systems with Apple silicon, and ARM64 will launch the game natively on Apple silicon, without additional software for compatibility.

ARM64 marks a performance increase when playing Baldur’s Gate 3, however at this time Steam and GOG Galaxy do not support ARM64 so the ARM64 game version can not use platform features such as Cross-Save, Steam/GOG Galaxy overlay, friends lists and multiplayer invite features. Please use the Rosetta option in the Launcher to continue having full Steam and GOG Galaxy integration.