Complementarity and complementarity both refer to the relationship between two angles. In junior high school, they all refer to the angle itself being between 0 ~ 180.

Complementarity: ∠ A+∠ B = 90, which is commonly found in right triangles, high-line triangles and triangles with round diameters.

Complementarity: ∠ A+∠ B = 180 is generally used for parallel lines, parallelograms, trapeziums, two angles opposite to a bisector arc, and so on.