Yes, there are different formats. The most common ones are called fixed jackpots. As the name suggests, the prize value remains unchanged. That doesn't mean the values are low, quite the opposite. There are online jackpots that offer a huge amount of money! Now, for those who like excitement, nothing beats trying your luck on slots that offer progressive rewards.
These jackpots increase with each play until a lucky person is blessed by the casino gods and hits a winning combination. There are also local jackpots, exclusively offered by a certain casino.