western kingbird vs kingbird

western kingbird and kingbird both are nouns.

Word	Noun	Adjective	Verb	Adverb
western kingbird	Yes	No	No	No
kingbird	Yes	No	No	No

As nouns, kingbird is a hypernym of western kingbird; that is, kingbird is a word with a broader meaning than western kingbird:

western kingbird: a kingbird seen in western United States; head and back are pale grey and the breast is yellowish and the tail is black
kingbird: large American flycatcher

Other hypernyms of western kingbird include Tyrannus tyrannus.

western kingbird (noun)	kingbird (noun)
a kingbird seen in western United States; head and back are pale grey and the breast is yellowish and the tail is black	large American flycatcher