dialectology vs philology

dialectology and philology both are nouns.

Word	Noun	Adjective	Verb	Adverb
dialectology	Yes	No	No	No
philology	Yes	No	No	No

As nouns, philology is a hypernym of dialectology; that is, philology is a word with a broader meaning than dialectology:

dialectology: the branch of philology that is devoted to the study of dialects
philology: the humanistic study of language and literature

Other hypernyms of dialectology include linguistics.

dialectology (noun)	philology (noun)
the branch of philology that is devoted to the study of dialects	the humanistic study of language and literature