The Diff method is similar to the Simple Sequence method, in that it fetches the last 10 fixtures of both home and away teams and calculate a form score based on following

HOME WIN = 3pts
HOME DRAW = 1pt
AWAY DRAW = 2pts
AWAY PTS = 4pts
HOME LOSS = 0pts
AWAY LOSS = 0pts

The Diff score is then calculated by subtracting the Home teams score from the Away teams score.