kinfolk vs family line

kinfolk and family line both are nouns.

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

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

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

kinfolk (noun)	family line (noun)
people descended from a common ancestor	people descended from a common ancestor