fascicle vs fasciculus

fascicle and fasciculus both are nouns.

Word	Noun	Adjective	Verb	Adverb
fascicle	Yes	No	No	No
fasciculus	Yes	No	No	No

As nouns, fascicle and fasciculus are synonyms defined as:

Other synonyms of fascicle include fiber bundle, fibre bundle.

fascicle (noun)	fasciculus (noun)
a bundle of fibers (especially nerve fibers)	a bundle of fibers (especially nerve fibers)
an installment of a printed work