cable television vs cable system

cable television and cable system both are nouns.

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

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

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

Other synonyms of cable television include cable, cable television service.

cable television (noun)	cable system (noun)
a television system that transmits over cables	a television system that transmits over cables
television that is transmitted over cable directly to the receiver