filmy fern vs film fern

filmy fern and film fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
filmy fern	Yes	No	No	No
film fern	Yes	No	No	No

As nouns, filmy fern and film fern are synonyms defined as:

filmy fern and film fern: any fern of the genus Hymenophyllum growing in tropical humid regions and having translucent leaves

filmy fern (noun)	film fern (noun)
any fern of the genus Hymenophyllum growing in tropical humid regions and having translucent leaves	any fern of the genus Hymenophyllum growing in tropical humid regions and having translucent leaves
any fern of the genus Trichomanes having large pinnatifid often translucent fronds; most are epiphytic on tree branches and twigs or terrestrial on mossy banks