From what I've read, Prime members get full access to Audible Channels just like Audible members. In addition, Prime members get access to Prime exclusive content not available to Audible members.
Edit: the Prime exclusive content consists of a rotating selection 50+ full-length audiobooks in nine different categories. Each channel has anywhere from 5 to 7 audiobooks. Content is available for streaming only. Downloads not allowed.
Prime Exclusive Channels- Better Than The Movie
- You & Improved
- For All Generations
- Celebrity Voices: Classic Stories
- Truly Criminal
- Get Hooked: Series Starters
- Dramatic History
- Worlds Away: Sci-Fi Classics
- Editors' Choice