folk vs line of descent

folk and line of descent both are nouns.

Word	Noun	Adjective	Verb	Adverb
folk	Yes	No	No	No
line of descent	Yes	No	No	No

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

folk (noun)	line of descent (noun)
the traditional and typically anonymous music that is an expression of the life of people in a community	the hereditary derivation of an individual
people in general (often used in the plural)	the kinship relation between an individual and the individual's progenitors
a social division of (usually preliterate) people
people descended from a common ancestor