“a concept is a theory of a category” is my go-to framework here.
So there are two different theories of two different categories that share the same name, leading to a situation where there is are two distinct concepts sharing the same category name.
Category is religion.
Atheism is a religion. That’s one category called religion.
Atheism cannot be a religion. That’s another category called religion.
The theoretical categories sit in two distinct ontologies (or glossaries) and these glossaries point to two distinct worldviews with lots of shared words (category names) that point to quite distinct concepts.