A. In Texas Holdem, the shared cards can be used in many combinations to create a five card poker hand. In Omaha, two cards from the four cards dealt must be used, along with the community cards, to create the five card hand.
Since exactly two cards must be used from the hole cards in Omaha Poker, the play is much different from Texas Holdem. However, both games contain enough similarities that a player of one should be able to pick up the other game fairly easily if enough focus is given.
In Holdem, a flush can be made when the common cards hold three or more suited cards, but in Omaha, you have to have two of the suited cards in your hand.