recurrence vs reversion

recurrence and reversion both are nouns.

Word	Noun	Adjective	Verb	Adverb
recurrence	Yes	No	No	No
reversion	Yes	No	No	No

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

Other hyponyms of recurrence include atavism, throwback, flashback.

recurrence (noun)	reversion (noun)
happening again (especially at regular intervals)	a failure to maintain a higher state
	turning in the opposite direction
	returning to a former state
	(genetics) a return to a normal phenotype (usually resulting from a second mutation)
	a reappearance of an earlier characteristic
	(law) an interest in an estate that reverts to the grantor (or his heirs) at the end of some period (e.g., the death of the grantee)