folks vs grass roots

folks and grass roots both are nouns.

Word	Noun	Adjective	Verb	Adverb
folks	Yes	No	No	No
grass roots	Yes	No	No	No

As nouns, grass roots is a hyponym of folks; that is, grass roots is a word with a more specific, narrower meaning than folks:

folks: people in general (often used in the plural)
grass roots: the common people at a local level (as distinguished from the centers of political activity)

folks (noun)	grass roots (noun)
your parents	the common people at a local level (as distinguished from the centers of political activity)
people in general (often used in the plural)	the essential foundation or source