There's only one side of the moon that faces the earth. It turns around the earth so that the same side of the moon always faces the earth. Consequently, this visible side of the moon is closest to the earth at all times. The portion of the earth that is closest to the moon is the portion that is facing the moon. Everything on earth including land, water, etc will be pulled towards the moon by the moon's gravitational attraction. As a result, it's always the portion of the earth closest to the moon which is facing the moon that feels the moons gravitational pull. The phases of the moon correspond to the angle of the suns rays shining on the moon as observed from earth. If the earth was exactly between the sun and moon, the moon would be totally dark and the tides and land on earth wouldn't be pulled as much toward the moon because the sun is pulling it in the opposite direction. Likewise when the moon is full that corresponds to a gravitational attraction towards the moon with the least amount of counter-pull by the sun. This results in the highest tides and land occuring on full moons.