wood pewee vs flycatcher

wood pewee and flycatcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
wood pewee	Yes	No	No	No
flycatcher	Yes	No	No	No

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

wood pewee: small olive-colored woodland flycatchers of eastern North America
flycatcher: large American birds that characteristically catch insects on the wing

Other hypernyms of wood pewee include New World flycatcher, tyrant bird, tyrant flycatcher.

wood pewee (noun)	flycatcher (noun)
small olive-colored woodland flycatchers of eastern North America	any of a large group of small songbirds that feed on insects taken on the wing
	large American birds that characteristically catch insects on the wing