There are several synonyms for the term "difference hierarchy." One such synonym is "distinction ladder," which highlights the idea of levels of hierarchical differences. Another synonym for difference hierarchy is "order of variance," which emphasizes the varying degrees of differences between objects or concepts. "Gradient of distinction" is another synonym that focuses on the gradual changes in hierarchical differences between elements. "Hierarchy of dissimilarity" is another option, which emphasizes the dissimilarities between objects arranged in a hierarchical order. Finally, "grade of differentiation" is a synonym that emphasizes the different degrees of variation in the hierarchy between different objects or entities.