western toad vs true toad

western toad and true toad both are nouns.

Word	Noun	Adjective	Verb	Adverb
western toad	Yes	No	No	No
true toad	Yes	No	No	No

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

western toad: of a great variety of habitats from southern Alaska to Baja California west of the Rockies
true toad: tailless amphibian similar to a frog but more terrestrial and having drier warty skin

western toad (noun)	true toad (noun)
of a great variety of habitats from southern Alaska to Baja California west of the Rockies	tailless amphibian similar to a frog but more terrestrial and having drier warty skin