gall gnat vs gallfly

gall gnat and gallfly both are nouns.

Word	Noun	Adjective	Verb	Adverb
gall gnat	Yes	No	No	No
gallfly	Yes	No	No	No

As nouns, gall gnat and gallfly are synonyms defined as:

gall gnat and gallfly: fragile mosquito-like flies that produce galls on plants

Other synonyms of gall gnat include gall midge.

gall gnat (noun)	gallfly (noun)
fragile mosquito-like flies that produce galls on plants	any of various insects that deposit their eggs in plants causing galls in which the larvae feed
	small solitary wasp that produces galls on oaks and other plants
	fragile mosquito-like flies that produce galls on plants