flycatcher vs oscine bird

flycatcher and oscine bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
flycatcher	Yes	No	No	No
oscine bird	Yes	No	No	No

As nouns, oscine bird is a hypernym of flycatcher; that is, oscine bird is a word with a broader meaning than flycatcher:

flycatcher: any of a large group of small songbirds that feed on insects taken on the wing
oscine bird: passerine bird having specialized vocal apparatus

Other hypernyms of flycatcher include oscine.

flycatcher (noun)	oscine bird (noun)
any of a large group of small songbirds that feed on insects taken on the wing	passerine bird having specialized vocal apparatus
large American birds that characteristically catch insects on the wing