phylum Arthropoda vs class Insecta

phylum Arthropoda and class Insecta both are nouns.

Word	Noun	Adjective	Verb	Adverb
phylum Arthropoda	Yes	No	No	No
class Insecta	Yes	No	No	No

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