reaction time vs interval

reaction time and interval both are nouns.

Word	Noun	Adjective	Verb	Adverb
reaction time	Yes	No	No	No
interval	Yes	No	No	No

As nouns, interval is a hypernym of reaction time; that is, interval is a word with a broader meaning than reaction time:

reaction time: the time that elapses between a stimulus and the response to it
interval: a definite length of time marked off by two instants

Other hypernyms of reaction time include time interval.

reaction time (noun)	interval (noun)
the time that elapses between a stimulus and the response to it	the distance between things
	a set containing all points (or all real numbers) between two given endpoints
	the difference in pitch between two notes
	a definite length of time marked off by two instants