What's the difference between the best move, a great move, and brilliant move?

Best, great and brilliant are all best moves, but best is just BEST, and great is when there is the only move that works, and a brilliant is something like a good sacrifice

Best: Exactly what it sounds like.

Great (!): The only good/reasonable move in any given position. Note that the move in question must actually be good. If all of your legal moves suck (zugzwang), but one in particular sucks less, it probably won't get a "great" rating.

Brilliant (!!): A move that sacrifices a piece or ignores a threat on one; however, no matter what your opponent does, it's their position that will worsen.

The engine doing the "Game review" is shallow and dumb. It can't be trusted. The "mistake and miss" were actually good moves.

Also. don't cheat.

There's still time to delete this. You're gonna get banned anyway.

You said "Great (!): The only good/reasonable move in any given position. Note that the move in question must actually be good."

I got a Great move in this game:

https://www.chess.com/analysis/game/pgn/12rWxj3WkN?tab=review&move=24

In this position I played Bh6+. However Nxc6 was either equally good or better. When I tried that move instead it gives this move a "best move". On Chessly.com Nxc6 is considered the top move.

Thoughts?

It's no surprise that different engines at different depths of analysis consider different moves as best.

But chess.com labeling Bh6+ as a "great move" is clearly a bug. It goes against their own definition of the term.

Also I noticed that Game Review Guy is talking complete nonsense about losing a queen with a fork. This isn't a surprise either, Game Review is just beyond awful.