motor neuron vs motor nerve fiber

motor neuron and motor nerve fiber both are nouns.

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

As nouns, motor neuron and motor nerve fiber are synonyms defined as:

motor neuron and motor nerve fiber: a neuron conducting impulses outwards from the brain or spinal cord

Other synonyms of motor neuron include efferent neuron, motoneuron.

motor neuron (noun)	motor nerve fiber (noun)
a neuron conducting impulses outwards from the brain or spinal cord	a neuron conducting impulses outwards from the brain or spinal cord