nosedive vs power dive

nosedive and power dive both are nouns.

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

As nouns, power dive is a hyponym of nosedive; that is, power dive is a word with a more specific, narrower meaning than nosedive:

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

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

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