christella vs fern

christella and fern both are nouns.

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

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

christella: any of several tropical ferns of the genus Christella having thin brittle fronds
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

christella (noun)	fern (noun)
any of several tropical ferns of the genus Christella having thin brittle fronds	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores