power user vs computer user

power user and computer user both are nouns.

Word	Noun	Adjective	Verb	Adverb
power user	Yes	No	No	No
computer user	Yes	No	No	No

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

power user: (computing) a computer user who needs the fastest and most powerful computers available
computer user: a person who uses computers for work or entertainment or communication or business

power user (noun)	computer user (noun)
(computing) a computer user who needs the fastest and most powerful computers available	a person who uses computers for work or entertainment or communication or business