Getting 21 (without it being a Blackjack) simply vastly increases your chances of beating the dealer, while getting Blackjack has the double advantage of both holding an unbeatable hand (at worst you tie if the dealer gets one as well) and paying out 1.5x times your bet, rather than just 1x your bet.
But the experienced Blackjack player will tell you that actually getting Blackjack is just a bonus and that it’s consistently edging out the Dealer that is the name of the game.
Rules: cards are worth their face value with all picture cards worth 10. An Ace is worth either 1 or 11.
Players are usually allowed to double up on their stake during the game if they hold a particular count (normally 9, 10 or 11) after two cards. They’re also allowed to split cards if the first two are the same. Some casinos allow you to do that when you draw any two identical cards, while others only allow you to split if you hold two identical picture cards.
Players can ask for as many additional cards as they want without getting more than 21, while Dealers have to take cards up to a score of 17 and don’t ever take any more once they have 17 or more; they go bust the same way as players do.
That’s how Blackjack works in a Land Casino and also how it works when playing it in Live Casino mode. Most Live Casinos offer you the choice of several Blackjack tables where not only is the Dealer different but the max and minimum stakes can also vary. Some tables also allow you to place additional side bets.