tyrant bird vs pewee

tyrant bird and pewee both are nouns.

Word	Noun	Adjective	Verb	Adverb
tyrant bird	Yes	No	No	No
pewee	Yes	No	No	No

As nouns, pewee is a hyponym of tyrant bird; that is, pewee is a word with a more specific, narrower meaning than tyrant bird:

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

tyrant bird (noun)	pewee (noun)
large American birds that characteristically catch insects on the wing	small olive-colored woodland flycatchers of eastern North America