variation vs activity

variation and activity both are nouns.

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

As nouns, activity is a hypernym of variation; that is, activity is a word with a broader meaning than variation:

variation (noun)	activity (noun)
an activity that varies from a norm or standard	any specific behavior
the act of changing or altering something slightly but noticeably from the norm or standard	the trait of being active; moving or acting rapidly and energetically
(ballet) a solo dance or dance figure	an organic process that takes place in the body
an artifact that deviates from a norm or standard	a process existing in or produced by nature (rather than by the intent of human beings)
something a little different from others of the same type	the state of being active
a repetition of a musical theme in which it is modified or embellished	(chemistry) the capacity of a substance to take part in a chemical reaction
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