family vs line of descent

family and line of descent both are nouns.

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

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

Other hypernyms of family include ancestry, blood, blood line, bloodline, descent, line, lineage, origin, parentage, pedigree, stemma, stock.

family (noun)	line of descent (noun)
primary social group; parents and children	the hereditary derivation of an individual
people descended from a common ancestor	the kinship relation between an individual and the individual's progenitors
a social unit living together
(biology) a taxonomic group containing one or more genera
a collection of things sharing a common attribute
an association of people who share common beliefs or activities
a loose affiliation of gangsters in charge of organized criminal activities
a person having kinship with another or others