line of descent vs ancestry

line of descent and ancestry both are nouns.

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

As nouns, line of descent and ancestry are synonyms defined as:

line of descent and ancestry: the hereditary derivation of an individual

Other synonyms of line of descent include blood, blood line, bloodline, descent, line, lineage, origin, parentage, pedigree, stemma, stock.

line of descent (noun)	ancestry (noun)
the hereditary derivation of an individual	inherited properties shared with others of your bloodline
the kinship relation between an individual and the individual's progenitors	the hereditary derivation of an individual