power plant vs powerhouse

power plant and powerhouse both are nouns.

Word	Noun	Adjective	Verb	Adverb
power plant	Yes	No	No	No
powerhouse	Yes	No	No	No

As nouns, power plant and powerhouse are synonyms defined as:

Other synonyms of power plant include power station.

power plant (noun)	powerhouse (noun)
an electrical generating station	an electrical generating station
	a team considered to be the best of its class
	a highly energetic and indefatigable person