power-dive vs plunge

power-dive is not a noun while plunge is a noun.

Word	Noun	Adjective	Verb	Adverb
power-dive	No	No	Yes	No
plunge	Yes	No	Yes	No

As verbs, plunge is a hypernym of power-dive; that is, plunge is a word with a broader meaning than power-dive:

Other hypernyms of power-dive include dive, plunk.

power-dive (noun)	plunge (noun)
	a brief swim in water
	a steep and rapid fall

power-dive (verb)	plunge (verb)
make a power dive	begin with vigor
	devote (oneself) fully to
	cause to be immersed
	immerse briefly into a liquid so as to wet, coat, or saturate
	thrust or throw into
	fall abruptly
	drop steeply
	dash violently or with great speed or impetuosity