line of descent vs bloodline

line of descent and bloodline both are nouns.

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

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

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

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

line of descent (noun)	bloodline (noun)
the hereditary derivation of an individual	ancestry of a purebred animal
the kinship relation between an individual and the individual's progenitors	the hereditary derivation of an individual