Dialect
A variety of a language. Where the line falls between a dialect and a language is often contested.
ELCat states the problem rather than resolving it: a variety’s “status as a ‘language’ or ‘dialect’ may simply remain contested, depending on who is talking about them”, and the differences are “nuanced and complicated, and dependent on wider issues like political, historical, economic, and sociocultural context”.
Glottolog is equally candid about its own limits here, noting that it “spent little effort on making dialect classifications consistent” and that much of its dialect data “contains numerous errors and inconsistencies”.
This matters on at least one profile in this Atlas: Glottolog records Griko as a dialect node rather than a language, and has no language-level entry for it. The profile treats it as a language. That is an editorial position, and the fact that a respected catalogue disagrees is worth knowing rather than smoothing over.