Basically Omaha poker has the same rules that Texas Holdem Poker has with two main differences and these are:
Every player does not get the usual two pocket cards but gets four and has to use two of these four cards plus three of the community cards to make their hand
These two differences means their is a very different strategy involved in playing Omaha Poker.
Omaha Hi/Low has the same rules as Omaha Poker however you can also win an extra piece of the pot
The player with the best poker hand will win what is called the "Hi " hand, also the player who has the "low" hand will also win a share of the pot, the low hand is defined as the lowest hand showing.
The Low hand is a hand with five cards below 9,
however two of the pocket cards must be used along with three of the community cards to make this low hand
I.e, 3, 4, 5, 6 and 8 of any suit would be classified as a Low hand, and only the very lowest of low hands wins.
The pot is divided in two and both winners share this pot, should more than one player have the same winning hand then they share the pot accordingly.
It is worth noting that on occasions there may not be enough lower cards dealt to ensure a low hand can be made by any player.
The lowest hand in Omaha hi/low is the 5,4,3,2,A of any suits as straights and/or flushed have no relevance in the low hand
and an Ace counts as both high and low and can be used to make a high hand and a low hand.