power service vs power company

power service and power company both are nouns.

Word	Noun	Adjective	Verb	Adverb
power service	Yes	No	No	No
power company	Yes	No	No	No

As nouns, power service and power company are synonyms defined as:

power service and power company: a public utility that provides electricity

Other synonyms of power service include electric company, light company.

power service (noun)	power company (noun)
a public utility that provides electricity	a public utility that provides electricity