wood warbler vs true warbler

wood warbler and true warbler both are nouns.

Word	Noun	Adjective	Verb	Adverb
wood warbler	Yes	No	No	No
true warbler	Yes	No	No	No

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

Other hypernyms of wood warbler include Old World warbler.

wood warbler (noun)	true warbler (noun)
small bright-colored American songbird with a weak unmusical song	small active brownish or greyish Old World birds
European woodland warbler with dull yellow plumage