fishing worm vs class Oligochaeta

fishing worm and class Oligochaeta both are nouns.

Word	Noun	Adjective	Verb	Adverb
fishing worm	Yes	No	No	No
class Oligochaeta	Yes	No	No	No

fishing worm (noun)	class Oligochaeta (noun)
terrestrial worm that burrows into and helps aerate soil; often surfaces when the ground is cool or wet; used as bait by anglers	earthworms