variation vs deviation

variation and deviation both are nouns.

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

As nouns, deviation is a hyponym of variation; that is, deviation is a word with a more specific, narrower meaning than variation:

variation (noun)	deviation (noun)
an activity that varies from a norm or standard	deviate behavior
the act of changing or altering something slightly but noticeably from the norm or standard	a turning aside (of your course or attention or concern)
(ballet) a solo dance or dance figure	the error of a compass due to local magnetic disturbances
an artifact that deviates from a norm or standard	the difference between an observed value and the expected value of a variable or function
something a little different from others of the same type	a variation that deviates from the standard or norm
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