blood line vs parentage

blood line and parentage both are nouns.

Word	Noun	Adjective	Verb	Adverb
blood line	Yes	No	No	No
parentage	Yes	No	No	No

As nouns, blood line and parentage are synonyms defined as:

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

blood line (noun)	parentage (noun)
the hereditary derivation of an individual	the hereditary derivation of an individual
	the kinship relation of an offspring to the parents
	the state of being a parent