class Insecta vs order Diptera

class Insecta and order Diptera both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Insecta	Yes	No	No	No
order Diptera	Yes	No	No	No

class Insecta (noun)	order Diptera (noun)
insects; about five-sixths of all known animal species	a large order of insects having a single pair of wings and sucking or piercing mouths; includes true flies and mosquitoes and gnats and crane flies