How exactly do agencies differ in Tagline ratings?

Question

contextual advertising

What is the difference between Digital Production and just Digital Agencies? How are they different from SMM agencies? Etc.
It is not entirely clear what is meant, because in fact these are all digital agencies, and if I understand correctly, these are ratings that show the strengths of agencies, for example, if your agency is great at SMM, then you are on this list, if you still and you draw the design cool, then you will also be on that list, right? No? correct, explain.