drosophila vs fruit fly

drosophila and fruit fly both are nouns.

Word	Noun	Adjective	Verb	Adverb
drosophila	Yes	No	No	No
fruit fly	Yes	No	No	No

As nouns, fruit fly is a hypernym of drosophila; that is, fruit fly is a word with a broader meaning than drosophila:

drosophila: small fruit fly used by Thomas Hunt Morgan in studying basic mechanisms of inheritance
fruit fly: any of numerous small insects whose larvae feed on fruits

Other hypernyms of drosophila include pomace fly.

drosophila (noun)	fruit fly (noun)
small fruit fly used by Thomas Hunt Morgan in studying basic mechanisms of inheritance	any of numerous small insects whose larvae feed on fruits