There are several synonyms for the phrase "resemble superficially," including "look alike but not really," "appear to be similar without actually being so," "bear a passing resemblance," and "share only a surface resemblance." Other potential synonyms could include "seem alike from a distance," "give the impression of similarity without truly matching," or "have a surface-level likeness that does not hold up upon closer examination." In any case, when two things resemble each other superficially, it means that they may look similar on the surface, but there are often significant differences upon closer examination.