These three expressions sound similar but answer different questions. Percentage change needs an original value. Percentage difference treats both values equally. Percentage points compare two values that are already percentages. State the question first; the same pair of numbers can legitimately produce different answers.
Use percentage change when direction matters
From 80 to 100 is a 25% increase because 80 is the original base. From 100 back to 80 is a 20% decrease because 100 is now the base. The two answers differ because the reference changed. This asymmetry is expected, not a rounding error.
Use percentage difference when neither value is original
For two measurements or peer values, divide the absolute difference by their average. For 80 and 100: 20 ÷ 90 × 100 = 22.222222%. Swapping the values leaves the answer unchanged. When both values are zero, the result cannot be calculated because the average base is zero.
Use percentage points for two percentages
A rate rising from 20% to 25% gains 5 percentage points. Relative to the original 20%, that is a 25% increase. Reporting only “up 5%” is ambiguous. Name percentage points for the direct subtraction and percentage change for the relative comparison.