power dive vs nosedive

power dive and nosedive both are nouns.

Word	Noun	Adjective	Verb	Adverb
power dive	Yes	No	No	No
nosedive	Yes	No	Yes	No

As nouns, nosedive is a hypernym of power dive; that is, nosedive is a word with a broader meaning than power dive:

power dive: a dive of an airplane that is accelerated both by gravity and by the power of the engine
nosedive: a steep nose-down descent by an aircraft

Other hypernyms of power dive include dive, nose dive.

power dive (noun)	nosedive (noun)
a dive of an airplane that is accelerated both by gravity and by the power of the engine	a steep nose-down descent by an aircraft
	a sudden sharp drop or rapid decline

power dive (verb)	nosedive (verb)
	plunge nose first; drop with the nose or front first, of aircraft