service vs utility

service and utility both are nouns.

Word	Noun	Adjective	Verb	Adverb
service	Yes	No	Yes	No
utility	Yes	Yes	No	No

As nouns, utility is a hyponym of service; that is, utility is a word with a more specific, narrower meaning than service:

service: work done by one person or group that benefits another
utility: the service (electric power or water or transportation) provided by a public utility

Other hyponyms of service include consulting service, facility, national service, hot line, hotline.

As nouns, utility is a hyponym of service; that is, utility is a word with a more specific, narrower meaning than service:

service: a company or agency that performs a public service; subject to government regulation
utility: a company that performs a public service; subject to government regulation

Other hyponyms of service include public-service corporation, public utility, public utility company.

service (noun)	utility (noun)
an act of help or assistance; something (such as a tool, software or system) used to render said help or assistance	the service (electric power or water or transportation) provided by a public utility
the act of public worship following prescribed rules	a facility composed of one or more pieces of equipment connected to or part of a structure and designed to provide a service such as heat or electricity or water or sewage disposal
(sports) a stroke that puts the ball in play	the quality of being of practical use
the act of mating by male animals	(computer science) a program designed for general support of the processes of a computer
the act of delivering a writ or summons upon someone	a company that performs a public service; subject to government regulation
periodic maintenance on a car or machine	(economics) a measure that is to be maximized in any situation involving choice
the performance of duties by a waiter or servant
employment in or work for another
work done by one person or group that benefits another
(law) the acts performed by an English feudal tenant for the benefit of his lord which formed the consideration for the property granted to him
tableware consisting of a complete set of articles (silver or dishware) for use at table
a means of serving
a force that is a branch of the armed forces
a company or agency that performs a public service; subject to government regulation

service (adjective)	utility (adjective)
	used of beef; usable but inferior
	capable of substituting in any of several positions on a team