nonrapid eye movement vs NREM sleep

nonrapid eye movement and NREM sleep both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonrapid eye movement	Yes	No	No	No
NREM sleep	Yes	No	No	No

As nouns, nonrapid eye movement and NREM sleep are synonyms defined as:

nonrapid eye movement and NREM sleep: a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur; accounts for about 75% of normal sleep time

Other synonyms of nonrapid eye movement include nonrapid eye movement sleep, NREM, orthodox sleep.

nonrapid eye movement (noun)	NREM sleep (noun)
a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur; accounts for about 75% of normal sleep time	a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur; accounts for about 75% of normal sleep time