you get 4 cards instead of 2. in the end your 2 best cards out of the 4 you hold are use to make the best 5 cards hand using 3 community cards. the betting, you can only bet anything up to what the current pot is. since you have 4 cards instead of 2 you have more chances of making a better hand on the turn and in the river. like a straight, full, flushes are more common in PLO. I love this game, it's a game to make a lot of money real quick if you know how to be patient and wait your turn and if you're lucky!
It's pretty straight forward only you get 4 hole cards instead of two and the maximum bet is limited to the pot size.
With the addition of two more hole cards as you can well imagine it generally takes a stronger hand to win the pot.