night vision vs sight

night vision and sight both are nouns.

Word	Noun	Adjective	Verb	Adverb
night vision	Yes	No	No	No
sight	Yes	No	Yes	No

As nouns, sight is a hypernym of night vision; that is, sight is a word with a broader meaning than night vision:

Other hypernyms of night vision include vision, visual modality, visual sense.

night vision (noun)	sight (noun)
the ability to see in reduced illumination (as in moonlight)	the act of looking or seeing or observing
	the ability to see; the visual faculty
	an instance of visual perception
	the range of vision
	a range of mental vision
	a place of interest, especially to visitors
	anything that is seen
	(often followed by `of') a large number or amount or extent

night vision (verb)	sight (verb)
	catch sight of; to perceive with the eyes
	take aim by looking through the sights of a gun (or other device)