biopsy vs diagnostic test

biopsy and diagnostic test both are nouns.

Word	Noun	Adjective	Verb	Adverb
biopsy	Yes	No	No	No
diagnostic test	Yes	No	No	No

As nouns, diagnostic test is a hypernym of biopsy; that is, diagnostic test is a word with a broader meaning than biopsy:

biopsy: examination of tissues or liquids from the living body to determine the existence or cause of a disease
diagnostic test: an assay conducted for diagnostic purposes

Other hypernyms of biopsy include diagnostic assay.

biopsy (noun)	diagnostic test (noun)
examination of tissues or liquids from the living body to determine the existence or cause of a disease	an assay conducted for diagnostic purposes