medullary sheath vs myelin sheath

medullary sheath and myelin sheath both are nouns.

Word	Noun	Adjective	Verb	Adverb
medullary sheath	Yes	No	No	No
myelin sheath	Yes	No	No	No

As nouns, medullary sheath and myelin sheath are synonyms defined as:

medullary sheath and myelin sheath: a layer of myelin encasing (and insulating) the axons of medullated nerve fibers

medullary sheath (noun)	myelin sheath (noun)
a layer of myelin encasing (and insulating) the axons of medullated nerve fibers	a layer of myelin encasing (and insulating) the axons of medullated nerve fibers