rapid eye movement vs paradoxical sleep

rapid eye movement and paradoxical sleep both are nouns.

Word	Noun	Adjective	Verb	Adverb
rapid eye movement	Yes	No	No	No
paradoxical sleep	Yes	No	No	No

As nouns, rapid eye movement and paradoxical sleep are synonyms defined as:

rapid eye movement and paradoxical sleep: a recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep

Other synonyms of rapid eye movement include rapid eye movement sleep, REM, REM sleep.

rapid eye movement (noun)	paradoxical sleep (noun)
a recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep	a recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep