variation vs vary

variation is a noun but vary is not a noun.

Word	Noun	Adjective	Verb	Adverb
variation	Yes	No	No	No
vary	No	No	Yes	No

variation (noun)	vary (noun)
an activity that varies from a norm or standard
the act of changing or altering something slightly but noticeably from the norm or standard
(ballet) a solo dance or dance figure
an artifact that deviates from a norm or standard
something a little different from others of the same type
a repetition of a musical theme in which it is modified or embellished
an instance of change; the rate or magnitude of change
(biology) an organism that has characteristics resulting from chromosomal alteration
(astronomy) any perturbation of the mean motion or orbit of a planet or satellite (especially a perturbation of the earth's moon)
the process of varying or being varied
the angle (at a particular location) between magnetic north and true north

variation (verb)	vary (verb)
	become different in some particular way, without permanently losing one's or its former characteristics or essence
	make something more diverse and varied
	be at variance with; be out of line with
	be subject to change in accordance with a variable