discrepancy vs deviation

discrepancy and deviation both are nouns.

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

As nouns, deviation is a hypernym of discrepancy; that is, deviation is a word with a broader meaning than discrepancy:

Other hypernyms of discrepancy include departure, difference, divergence.

discrepancy (noun)	deviation (noun)
a difference between conflicting facts or claims or opinions	deviate behavior
an event that departs from expectations	a turning aside (of your course or attention or concern)
	the error of a compass due to local magnetic disturbances
	the difference between an observed value and the expected value of a variable or function
	a variation that deviates from the standard or norm