u-turn vs turnabout

u-turn and turnabout both are nouns.

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

As nouns, turnabout is a hypernym of u-turn; that is, turnabout is a word with a broader meaning than u-turn:

Other hypernyms of u-turn include reversal, reverse, reversion, turnaround.

u-turn (noun)	turnabout (noun)
complete reversal of direction of travel	turning in the opposite direction
	a decision to reverse an earlier decision