A brilliant move is the best move and the difference is that a brilliant move is harder to find and gives material
This is absolutely not true.
What you wrote is a misconception that some user invented many years ago. It's nonsense, but it lives and spreads like a virus.
A "brilliant move" is sacrifice that is good. It is not necessarily the best move (but it has to be close). It not necessarily difficult to find: in fact, most "brilliant moves" are obvious short-term sacrifices that are very easy to find.
A brilliant move is the best move and the difference is that a brilliant move is harder to find and gives material