class Gastropoda vs subclass Amphineura

class Gastropoda and subclass Amphineura both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Gastropoda	Yes	No	No	No
subclass Amphineura	Yes	No	No	No

class Gastropoda (noun)	subclass Amphineura (noun)
snails and slugs and their relatives	a class of Gastropoda