bamboo fern vs fern

bamboo fern and fern both are nouns.

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

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

bamboo fern: fast-growing sturdy Japanese fern; cultivated for their attractive broad dark-green pinnate fronds
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

bamboo fern (noun)	fern (noun)
fast-growing sturdy Japanese fern; cultivated for their attractive broad dark-green pinnate fronds	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores