CAF (Core Audio Format) is a free audio container format developed by Apple and works on macOS 10.4 or later. It can also be opened on macOS 10.3 using QuickTime 7. Apart from audio, CAF can also hold multiple metadata such as file name, album name, composer, and more. It comes with a filename extension of .caf.
Apple QuickTime Player Soundtrack Pro Logic Studio
AAX (Atom Asset Exchange) is an audio file format for storing sound-based products from Audible Incorporated. Typically, AAX files are DRM protected, although they can be transcoded to other common formats such as MP3 using a licensed program like Wondershare UniConverter.