sheath vs neurolemma

sheath and neurolemma both are nouns.

Word	Noun	Adjective	Verb	Adverb
sheath	Yes	No	No	No
neurolemma	Yes	No	No	No

As nouns, neurolemma is a hyponym of sheath; that is, neurolemma is a word with a more specific, narrower meaning than sheath:

sheath: an enveloping structure or covering enclosing an animal or plant organ or part
neurolemma: thin membranous sheath around a nerve fiber

Other hyponyms of sheath include theca, lorica, medullary sheath, myelin sheath, neurilemma, husk.

sheath (noun)	neurolemma (noun)
a protective covering (as for a knife or sword)	thin membranous sheath around a nerve fiber
a dress suitable for formal occasions
an enveloping structure or covering enclosing an animal or plant organ or part