reversion vs about turn

reversion and about turn both are nouns.

Word	Noun	Adjective	Verb	Adverb
reversion	Yes	No	No	No
about turn	Yes	No	No	No

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

Other hyponyms of reversion include about-face, u-turn.

reversion (noun)	about turn (noun)
a failure to maintain a higher state	act of pivoting 180 degrees, especially in a military formation
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)