Pteridaceae vs fern family

Pteridaceae and fern family both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pteridaceae	Yes	No	No	No
fern family	Yes	No	No	No

As nouns, fern family is a hypernym of Pteridaceae; that is, fern family is a word with a broader meaning than Pteridaceae:

Pteridaceae: one of a number of families into which the family Polypodiaceae has been subdivided in some classification systems; Pteridaceae is itself in turn sometimes further subdivided
fern family: families of ferns and fern allies

Pteridaceae (noun)	fern family (noun)
one of a number of families into which the family Polypodiaceae has been subdivided in some classification systems; Pteridaceae is itself in turn sometimes further subdivided	families of ferns and fern allies