orthodox sleep vs NREM

orthodox sleep and NREM both are nouns.

Word	Noun	Adjective	Verb	Adverb
orthodox sleep	Yes	No	No	No
NREM	Yes	No	No	No

As nouns, orthodox sleep and NREM are synonyms defined as:

orthodox sleep and NREM: 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 orthodox sleep include nonrapid eye movement, nonrapid eye movement sleep, NREM sleep.

orthodox sleep (noun)	NREM (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