Brilliant move 39. Kc5

In the game above I got my first brilliant move 39. Kc5. I don't know why Kc5 is a brilliant move it looked like a very normal move.

Cause it protect the asset... black pawn at f6 and king at d3 stopping you from going to e4 & 5 and c4. If you move to c6, d6, e6, you would lost the pawn. It also protect the pawn to reach the promotion it need.

Yes I know, to protect the pawn and let it promote. I have done moves exactly like it in other games but they only got a best move. So what is the difference between a brilliant and best move.  

From what I know so far, best moves are the moves found and assessed as best by the engine (whether you played it or not). Brilliant moves on the other hand was done by player when it outperform the moves propose by the engine.

Hardly brilliant, because 37.Kc6 is equally good- both moves result in the same balanced position (both sides promote to Queen).

Black simply went nuts by hunting the d3 pawn instead of pushing his passed f- one.