A lookup table of normative specifications for every API call is Reference material. But a tour of API concepts is not (that would be Explanation). Nor is a Tut

A lookup table of normative specifications for every API call is Reference material. But a tour of API concepts is not (that would be Explanation). Nor is a Tutorial that introduces the API. A lookup table of normative specifications of CLI arguments would also be Reference. So they are not synonymous. To be clear, I'm not advocating for navigation that must always have this structure in cases where it's redundant. I think people should do what makes sense. But I think it is nevertheless useful to not mix the different categories.