It makes a world of difference when you consider it in the context of American history.
Race and the other legally protected classes have been the biggest factors in discrimination in this country - the biggest ways in which US society has violated its creed "We hold these truths to be self evident that all men are created equal".
Political party has not, nor has "users of a computer application", nor the intersection of those manifested in Parler.
But sure, if you algebraically treat race and political party as equivalents without any historical context, the comparison is "in principle" the same, but that is deeply flawed as it requires the conscious exclusion of historical context.
Race is a protected class per the law. Parler is not