They are two different things, and not every game has both.
Progressive jackpot: a special prize that grows with a small part of many players' bets. When someone wins it, it starts again from a base amount. It only exists in games that show it on screen.
Fixed jackpot: a special prize with a fixed amount that does not grow over time.
Maximum win: the most a game can pay in one round. It is shown as a multiple of the bet, for example 5,000x. If a round reaches that limit, it ends and that amount is paid.
Many slots have no jackpot: they have a maximum win. The big wins that come up in free spins, for example 50 or 100 times the bet, are regular game prizes and not a jackpot.
The maximum win and jackpots come up very rarely, and no previous result makes the next one more likely. To see what each game has, open its rules with the information button (i) inside the game.