fruit fly vs pomace fly

fruit fly and pomace fly both are nouns.

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

As nouns, fruit fly and pomace fly are synonyms defined as:

fruit fly and pomace fly: any of numerous small insects whose larvae feed on fruits

fruit fly (noun)	pomace fly (noun)
any of numerous small insects whose larvae feed on fruits	any of numerous small insects whose larvae feed on fruits