reversal vs u-turn

reversal and u-turn both are nouns.

Word	Noun	Adjective	Verb	Adverb
reversal	Yes	No	No	No
u-turn	Yes	No	No	No

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

Other hyponyms of reversal include about-face, about turn.

reversal (noun)	u-turn (noun)
a change from one state to the opposite state	complete reversal of direction of travel
the act of reversing the order or place of
turning in the opposite direction
a major change in attitude or principle or point of view
a judgment by a higher court that the judgment of a lower court was incorrect and should be set aside
a decision to reverse an earlier decision
turning in an opposite direction or position
an unfortunate happening that hinders or impedes; something that is thwarting or frustrating