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).
Spanish 21 is similar to traditional Blackjack but with more options and payouts. One difference is that all numbered 10 cards are removed from the deck leaving 48 cards in each deck. Jacks, Queens and Kings count as 10. Aces count as 1 or 11 (whatever is to the Player's advantage).