folk vs family line

folk and family line both are nouns.

Word	Noun	Adjective	Verb	Adverb
folk	Yes	No	No	No
family line	Yes	No	No	No

As nouns, folk and family line are synonyms defined as:

Other synonyms of folk include family, kinfolk, kinsfolk, phratry, sept.

folk (noun)	family line (noun)
the traditional and typically anonymous music that is an expression of the life of people in a community	people descended from a common ancestor
people in general (often used in the plural)
a social division of (usually preliterate) people
people descended from a common ancestor