Omaha High is a flop game with a blind structure, similar to Texas Hold'em. A feature of Omaha is that you receive four hole cards instead of two.
While the betting and game play is the same as Hold'em, your final hand is made up of any two of your hole cards and and three of the board. Remember you must use two of your hole cards. The following sample hand demonstrates the difference.
Hole Cards; As, Ac, 10d, 9h.
Board Cards; Qs, 7s, 9c, 5s, 2s
Best Hold'em hand possible; As, Qs, 7s, 5s, 2s, an Ace High Flush.
Best Omaha High hand possible; As, Ac, Qs, 9c, 7s, a pair of Aces.
In Hold'em you would have an Ace high flush, the nut hand on that board. In Omaha because you must use 2 of your hole cards you have a pair of Aces, that's all. Be warned, it is not uncommon for the winning hand to be at least a straight, particularly at a full table.
I'll say that again just to be sure. High card, pairs, two pair or trips rarely win at a full table.
Omaha Hi/Lo 8's or Better
If you have never played a Hi/Lo split game before watch out! Omaha 8's or Better allows for 2 pots, a High pot won by the standard High poker hand and possibly a Low hand won by the lowest 5 unpaired cards valued 8 or less. Where a Low hand is in evidence the pot will be split 50/50.
Aces can be played as High or Low cards.
Low hands are possible when at least three unpaired cards valued 8 or lower are on the board. The Low hand that wins will have the lowest high card. Where there is a tie for high card the next highest card will decide. i.e. A,2,4,5,8 beats A,2,5,7,8 .
Flushes and straights are not considered when judging the Low hand, the hand with the 5 lowest unpaired cards valued 8 or under wins.
The best starting hands for Omaha 8 are those where you have the chance to win both the High and Low hand. (scooping the pot).
Good luck at the tables,