The position is called under the gun (UTG) when it is located after the big blind. This position is a big disadvantage because we must then speak first after the distribution of the cards (pre-flop) and then decide to pass (fold), pay or follow (call), or then raise (raise). of the "flop", the first to speak is the player who is "small blind".
It is called "At the button" when you are the dealer (Dealer). This position is the best because you speak last after the flop. For other positions, the tactical situation deteriorates as the button moves to the left, until the small blind.