High school soccer is scored by the same point system that is used in the MLS. When the ball passes over the opposing team's goal line, your team scores 1 point.
The most notable difference between high school soccer and professional soccer is the size of the field. Professional soccer fields range from 105 to 120 yards long, and from 70 to 77 yards wide. By comparison, high school soccer fields are generally 110 yards long by 65 yards wide, and in some cases smaller.
FIFA is the worldwide soccer governing association. Their main responsibility is overseeing the rules of the game and updating as needed over time to ensure player safety. From youth and high school soccer, all the way up to the MLS, soccer games throughout the world follow the regulations set forth by FIFA.