nose dive vs power dive

nose dive and power dive both are nouns.

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

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

nose dive: 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

nose dive (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