power company vs light company

power company and light company both are nouns.

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

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

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

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

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