telecommunication system vs telecom system

telecommunication system and telecom system both are nouns.

Word	Noun	Adjective	Verb	Adverb
telecommunication system	Yes	No	No	No
telecom system	Yes	No	No	No

As nouns, telecommunication system and telecom system are synonyms defined as:

telecommunication system and telecom system: a communication system for communicating at a distance

Other synonyms of telecommunication system include telecom equipment, telecommunication equipment.

telecommunication system (noun)	telecom system (noun)
a communication system for communicating at a distance	a communication system for communicating at a distance