Quantum chess is a variant of the traditional game of chess that incorporates elements of quantum mechanics. This makes it different from classical chess in several ways.

One of the main differences is that, in quantum chess, each piece on the board is represented by a quantum state, which can exist in multiple positions at the same time. This allows for the possibility of superposition, entanglement, and other quantum phenomena in the game. In classical chess, on the other hand, each piece can only be in one position at a time, and the rules of the game do not allow for the possibility of quantum phenomena.

Another difference is that, in quantum chess, players can choose to either move a piece to a new position, or apply a quantum operation to it, such as a rotation or a reflection. This allows for the possibility of multiple moves at the same time, and for pieces to move to seemingly impossible positions. In classical chess, on the other hand, players can only move their pieces to a new position, and the rules of the game do not allow for the possibility of applying quantum operations to pieces.

Finally, the rules of quantum chess are different from those of classical chess. In quantum chess, there are additional rules that account for the unique features of quantum mechanics, such as the superposition and entanglement rules. In classical chess, on the other hand, the rules are based solely on the traditional rules of the game.

Overall, quantum chess is a fundamentally different game from classical chess, due to the incorporation of quantum mechanics into its rules and gameplay. While the game is still in the development stage, it has already attracted a dedicated community of players and enthusiasts.