family Athyriaceae vs class Filicopsida

family Athyriaceae and class Filicopsida both are nouns.

Word	Noun	Adjective	Verb	Adverb
family Athyriaceae	Yes	No	No	No
class Filicopsida	Yes	No	No	No

family Athyriaceae (noun)	class Filicopsida (noun)
alternative names for one of a number of families into which the family Polypodiaceae has been subdivided in some classification systems	ferns