Is "No Fail" Cheat in Guitar Hero 3 the Same as a Bot?

No, they're fundamentally different.

• No Fail Cheat: Disables failure—you still play, press buttons, but missed notes don't end the song. It's an "easy mode" for learning/practice.
• Bot: Automated program plays perfectly with zero human input, even on Expert difficulty.

No Fail keeps you engaged; bots remove all skill/effort. Bots ultimately diminish the challenge and fun of learning.