bell toad vs toad frog

bell toad and toad frog both are nouns.

Word	Noun	Adjective	Verb	Adverb
bell toad	Yes	No	No	No
toad frog	Yes	No	No	No

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

bell toad: western North American frog with a taillike copulatory organ
toad frog: any of various tailless stout-bodied amphibians with long hind limbs for leaping; semiaquatic and terrestrial species

Other hypernyms of bell toad include anuran, batrachian, frog, salientian, toad.

bell toad (noun)	toad frog (noun)
western North American frog with a taillike copulatory organ	any of various tailless stout-bodied amphibians with long hind limbs for leaping; semiaquatic and terrestrial species