film fern vs fern

film fern and fern both are nouns.

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

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

film fern: any fern of the genus Hymenophyllum growing in tropical humid regions and having translucent leaves
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

film fern (noun)	fern (noun)
any fern of the genus Hymenophyllum growing in tropical humid regions and having translucent leaves	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores