class Hexapoda vs Arthropoda

class Hexapoda and Arthropoda both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Hexapoda	Yes	No	No	No
Arthropoda	Yes	No	No	No

class Hexapoda (noun)	Arthropoda (noun)
insects; about five-sixths of all known animal species	jointed-foot invertebrates: arachnids, crustaceans, insects, millipedes, centipedes