Unlike some other shooting games, Overwatch is defined by roles and the fact that players from each team can play the same hero.
Oftentimes, the difference between losing and winning a game can come down to the performance of a specific hero or role on one team that overwhelms the same hero or role on the opposite team.
Over the past few years, players have started to explain that phenomenon with the shorthand abbreviation “diff.”
For instance, if the opposing team’s Widowmaker was chaining headshots in a match and your team’s Widow had no kills, one might attribute that loss to the “Widowmaker diff.”
The same can be said for roles as well. If your tanks consistently outplay the opposing team’s tanks, you could say that you’re winning because of a “tank diff.”
Regularly, teams will evaluate a loss by trying to figure out or agree on whether the loss can be attributed to a tank or DPS “diff.” This basically means “were our tanks not good enough or were our DPS bad?”
The phrase is also frequently used as a way to flex your prowess or trash talk players who are thought to have performed poorly. So watch out for the way you throw the phrase around if you’re trying to convince a teammate to cooperate with you.