A key difference between Blackjack and Spanish 21 is that all 10s are removed from the deck in Spanish 21. A Blackjack occurs when the first two cards that are dealt equal 21  a combination of a face card (Jack, Queen, or King) and an Ace (which can have a value of 1 or 11, depending on your hand).

Pontoon remains the name of the informal and domestic British game, and, as a two-card count of 21 is called a pontoon, the term has come to be used for a prison term of 21 months (or years, if you're not careful). In America the name Vingt-(et)-un was replaced by Blackjack early in the 20th century.