tyrant bird vs kingbird

tyrant bird and kingbird both are nouns.

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

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

tyrant bird: large American birds that characteristically catch insects on the wing
kingbird: large American flycatcher

tyrant bird (noun)	kingbird (noun)
large American birds that characteristically catch insects on the wing	large American flycatcher