quillwort family vs fern family

quillwort family and fern family both are nouns.

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

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

quillwort family (noun)	fern family (noun)
quillworts; coextensive with the genus Isoetes	families of ferns and fern allies