A player total of 21 on the first two cards is a "natural" or "blackjack", and the player wins immediately unless the dealer also has one, in which case the hand ties. In the case of a tie ("push" or "standoff"), bets are returned without adjustment.
Blackjack and 21 are essentially the same game, with the objective being to reach a hand value of 21 or as close to it as possible without going over. In some cases, the term "21" may be used to refer to the game played in a casual setting, while "Blackjack" is often used in a casino context.