The League Tiebreaker
In a rugby union or rugby league season, teams are awarded competition points for winning matches, drawing matches, and occasionally for scoring a high number of tries (Bonus Points).
When two teams finish the season tied on total competition points, the primary tiebreaker to determine who advances to the playoffs or wins the championship is their Points Difference (PD).
Measuring Dominance
Points Difference is identical in theory to Goal Difference in soccer. It is a pure mathematical measure of a team's total dominance across the entire season. A team with a massive, positive points difference has consistently blown out their opponents and maintained an ironclad defense.
The Formula
To calculate Points Difference, subtract the total points conceded across the season from the total points scored.
Points Difference = Points For (Scored) - Points Against (Conceded)
Strategic Implications
Because Points Difference is the primary tiebreaker, a team winning a match 40-10 will not simply stop playing or rest their players in the final ten minutes. They will continue to aggressively hunt for tries, knowing that padding their 'Points For' column could literally be the difference between winning a championship and finishing in second place months later.