gall gnat vs two-winged insects

gall gnat and two-winged insects both are nouns.

Word	Noun	Adjective	Verb	Adverb
gall gnat	Yes	No	No	No
two-winged insects	Yes	No	No	No

As nouns, two-winged insects is a hypernym of gall gnat; that is, two-winged insects is a word with a broader meaning than gall gnat:

gall gnat: fragile mosquito-like flies that produce galls on plants
two-winged insects: insects having usually a single pair of functional wings (anterior pair) with the posterior pair reduced to small knobbed structures and mouth parts adapted for sucking or lapping or piercing

Other hypernyms of gall gnat include dipteran, dipteron, dipterous insect.

gall gnat (noun)	two-winged insects (noun)
fragile mosquito-like flies that produce galls on plants	insects having usually a single pair of functional wings (anterior pair) with the posterior pair reduced to small knobbed structures and mouth parts adapted for sucking or lapping or piercing