In the opening scene, the poker player announces his hand as "aces and eights," but he had a full house, aces full of eights (three aces, two eights). No poker player would call that hand "aces and eights," as that refers to two pair (two aces, two eights, and an unrelated card), a lower-ranking hand.
Gaunt then compounds the mistake by telling him he had the Dean Man's Hand, but the Dead Man's Hand *is* aces and eights.
Gaunt then compounds the mistake by telling him he had the Dean Man's Hand, but the Dead Man's Hand *is* aces and eights.