instant vs moment

instant and moment both are nouns.

Word	Noun	Adjective	Verb	Adverb
instant	Yes	Yes	No	No
moment	Yes	No	No	No

As nouns, instant and moment are synonyms defined as:

Other synonyms of instant include minute, second.

As nouns, moment is a hypernym of instant; that is, moment is a word with a broader meaning than instant:

instant: a very short time (as the time it takes the eye to blink or the heart to beat)
moment: an indefinitely short time

Other hypernyms of instant include bit, minute, mo, second.

instant (noun)	moment (noun)
a particular point in time	having important effects or influence
a very short time (as the time it takes the eye to blink or the heart to beat)	the n-th moment of a distribution is the expected value of the n-th power of the deviations from a fixed value
	a turning force produced by an object acting at a distance (or a measure of that force)
	a particular point in time
	an indefinitely short time
	at this time