folk writer vs author

folk writer and author both are nouns.

Word	Noun	Adjective	Verb	Adverb
folk writer	Yes	No	No	No
author	Yes	No	Yes	No

As nouns, author is a hypernym of folk writer; that is, author is a word with a broader meaning than folk writer:

folk writer: a writer of folktales
author: writes (books or stories or articles or the like) professionally (for pay)

Other hypernyms of folk writer include writer.

folk writer (noun)	author (noun)
a writer of folktales	writes (books or stories or articles or the like) professionally (for pay)
	someone who originates or causes or initiates something

folk writer (verb)	author (verb)
	be the author of