Athyriaceae vs class Filicinae

Athyriaceae and class Filicinae both are nouns.

Word	Noun	Adjective	Verb	Adverb
Athyriaceae	Yes	No	No	No
class Filicinae	Yes	No	No	No

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