Objective reality shows that race is a spectrum, while gender is not. It also shows that race has at least a dozen different known "essential poles" which define all human racial variation, and probably hundreds more if you dig deep enough, while gender still has only 2.

However, in the sociopolitical sphere, liberals insist that gender is multivariate because otherwise that would hurt transpeople's feelings, and both liberals AND conservatives insist that race is rigidly defined, because that would hurt both "BIPOC" and "white" feelings respectively.

Race really is a social construct, while gender is not