Indian button fern vs fern

Indian button fern and fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
Indian button fern	Yes	No	No	No
fern	Yes	No	No	No

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

Indian button fern: fern of tropical Asia having round buttonlike bulbils
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

Indian button fern (noun)	fern (noun)
fern of tropical Asia having round buttonlike bulbils	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores