genus Pteridium vs fern genus

genus Pteridium and fern genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Pteridium	Yes	No	No	No
fern genus	Yes	No	No	No

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

genus Pteridium (noun)	fern genus (noun)
a genus of ferns belonging to the family Dennstaedtiaceae	genera of ferns and fern allies