得失球差
Goal difference (or points difference) is calculated as the number of goals (or points) scored in all league matches minus the number of goals or points conceded. Goal difference was first introduced as a tiebreaker in association football, at the 1970 FIFA World Cup, and was adopted by the Football League in England five years later. It has since spread to many other competitions, where it is typically used as either the first or, after tying teams' head-to-head records, second tiebreaker.