light company vs public utility

light company and public utility both are nouns.

Word	Noun	Adjective	Verb	Adverb
light company	Yes	No	No	No
public utility	Yes	No	No	No

As nouns, public utility is a hypernym of light company; that is, public utility is a word with a broader meaning than light company:

light company: a public utility that provides electricity
public utility: a company that performs a public service; subject to government regulation

Other hypernyms of light company include public-service corporation, public utility company, utility.

light company (noun)	public utility (noun)
a public utility that provides electricity	a company that performs a public service; subject to government regulation