The Steve Nash behind the back partner passing drill is going to work on ball handling and being able to pass with one hand right off the dribble. This type of pass would be used in a game when a player is dribbling the ball, and a teammate flashes open and there is only a small window of time to get them the ball. If the player handling the ball has to pick up the ball with both hands before making the pass, they may miss their chance to get the open teammate the ball. This is where the push pass comes into play. It allows the player to make a quick and accurate pass off of the dribble to the open teammate.
Basketball passing drills like this are great for basketball camps or times when you have a large number of players in basketball training. It keeps all of the players active at the same time, and it also works on two different skills during the same drill, which will help to maximize time.