When different chess engines play against each other, they don’t always have the same outcome. Why not?

Question

This has bugged me for a bit. If chess engines are meant to always play the best moves, then how come two chess engines playing against each other doesn’t always have the same winner?

In: Other

Answer 1

Chess isnt a solved game. The amount of possible games is so large that even with a computer we cannot come close to evaluating every possible game so we cant know what the best move is. Chess engines, like humans, try to make the best move based on limited information and their moves are way way better than any moves made by humans, but they are still not neccesarily the best possible move.