underwing vs noctuid

underwing and noctuid both are nouns.

Word	Noun	Adjective	Verb	Adverb
underwing	Yes	No	No	No
noctuid	Yes	No	No	No

As nouns, noctuid is a hypernym of underwing; that is, noctuid is a word with a broader meaning than underwing:

underwing: moth having dull forewings and brightly colored hind wings
noctuid: usually dull-colored medium-sized nocturnal moth; the usually smooth-bodied larvae are destructive agricultural pests

Other hypernyms of underwing include noctuid moth, owlet moth.

underwing (noun)	noctuid (noun)
moth having dull forewings and brightly colored hind wings	usually dull-colored medium-sized nocturnal moth; the usually smooth-bodied larvae are destructive agricultural pests