fiber vs nerve fiber

fiber and nerve fiber both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiber	Yes	No	No	No
nerve fiber	Yes	No	No	No

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

fiber: any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber)
nerve fiber: a threadlike extension of a nerve cell

Other hyponyms of fiber include muscle cell, muscle fiber, muscle fibre, nerve fibre.

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

fiber: a slender and greatly elongated substance capable of being spun into yarn
nerve fiber: a threadlike extension of a nerve cell

fiber (noun)	nerve fiber (noun)
a leatherlike material made by compressing layers of paper or cloth	a threadlike extension of a nerve cell
the inherent complex of attributes that determines a persons moral and ethical actions and reactions
any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber)
coarse, indigestible plant food low in nutrients; its bulk stimulates intestinal peristalsis
a slender and greatly elongated substance capable of being spun into yarn