reversal vs reversion

reversal and reversion both are nouns.

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

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

Other hyponyms of reversal include regress, regression, retrogression, retroversion.

As nouns, reversal and reversion are synonyms defined as:

Other synonyms of reversal include reverse, turnabout, turnaround.

reversal (noun)	reversion (noun)
a change from one state to the opposite state	a failure to maintain a higher state
the act of reversing the order or place of	turning in the opposite direction
turning in the opposite direction	returning to a former state
a major change in attitude or principle or point of view	(genetics) a return to a normal phenotype (usually resulting from a second mutation)
a judgment by a higher court that the judgment of a lower court was incorrect and should be set aside	a reappearance of an earlier characteristic
a decision to reverse an earlier decision	(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)
turning in an opposite direction or position
an unfortunate happening that hinders or impedes; something that is thwarting or frustrating