class Ophiuroidea vs subclass Euryalida

class Ophiuroidea and subclass Euryalida both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Ophiuroidea	Yes	No	No	No
subclass Euryalida	Yes	No	No	No

class Ophiuroidea (noun)	subclass Euryalida (noun)
brittle stars and basket stars	a subclass of basket stars