This document presents two new Boolean combination methods called "orthogonalizing difference-building" and "orthogonal OR-ing". These methods calculate the difference and complement of functions, as well as the EXOR and EXNOR of minterms or functions, resulting in orthogonal forms. Orthogonal forms have advantages for further calculations. The methods are based on set theory and treat minterms and functions as ternary-vector lists. Equations are provided to define the difference and disjunction of minterms or functions in terms of their ternary-vector list representations.