class Crustacea vs subclass Entomostraca

class Crustacea and subclass Entomostraca both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Crustacea	Yes	No	No	No
subclass Entomostraca	Yes	No	No	No

class Crustacea (noun)	subclass Entomostraca (noun)
class of mandibulate arthropods including: lobsters, crabs, shrimps, woodlice, barnacles, decapods, water fleas	in some older classifications includes the Branchiopoda and Copepoda and Ostracoda and Cirripedia; no longer in technical use