bull snake vs colubrid snake

bull snake and colubrid snake both are nouns.

Word	Noun	Adjective	Verb	Adverb
bull snake	Yes	No	No	No
colubrid snake	Yes	No	No	No

As nouns, colubrid snake is a hypernym of bull snake; that is, colubrid snake is a word with a broader meaning than bull snake:

bull snake: any of several large harmless rodent-eating North American burrowing snakes
colubrid snake: mostly harmless temperate-to-tropical terrestrial or arboreal or aquatic snakes

Other hypernyms of bull snake include colubrid.

bull snake (noun)	colubrid snake (noun)
any of several large harmless rodent-eating North American burrowing snakes	mostly harmless temperate-to-tropical terrestrial or arboreal or aquatic snakes