kinsfolk vs family line

kinsfolk and family line both are nouns.

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

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

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

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