cable system vs cable television service

cable system and cable television service both are nouns.

Word	Noun	Adjective	Verb	Adverb
cable system	Yes	No	No	No
cable television service	Yes	No	No	No

As nouns, cable system and cable television service are synonyms defined as:

cable system and cable television service: a television system that transmits over cables

Other synonyms of cable system include cable, cable television.

cable system (noun)	cable television service (noun)
a television system that transmits over cables	a television system that transmits over cables