The limit (or pot-limit) format is the most common playing format in Omaha while Omaha high and Omaha 8-or-better are its two most popular spread variations.
Omaha high is more like Texas Hold’em where each player aims to have the best high hand to win the pot.
In Omaha 8-or-better, the best high hand and the best low hand are awarded the pot.
For a player to have the best low hand, he must have five different cards with a rank of 8 or lower.