When people confuse relative terms with absolute terms

I see this one in politics. Presidential candidates A and B are very similar. They are both liberals. However, candidate B is a little more conservative than candidate A. So then, among liberals, candidate A is called liberal and candidate B is called conservative, even though both are liberal when compared to Candidate C, who is an actual conservative.

This happens in a lot of other areas. There is a vast spectrum between strict and lenient parenting. But then you have two sets of parents who are almost equally strict, but one slightly more strict than the other, and one is called strict and the other lenient, even though they are both strict.

Is there a name for this kind of bad reasoning?

This is how people like Sam Harris and Dave Rubin are called "conservative neo-Nazi's"... when they are both actual (secular) Jewish liberals. I wouldn't say that this is a fallacy, but rather that the person making the claim is simply factually wrong—by virtually all reasonable standards/interpretations of the definitions.

Sometimes, this gets into a gray area. For example, in your "strict/lenient" example. These are relative terms for the most part, or at least highly subjective. When we use these terms there should be an implied "compared to what/whom." Without stating that implication, we assume "the term as generally used as I understand it."