coordinate system vs reference system

coordinate system and reference system both are nouns.

Word	Noun	Adjective	Verb	Adverb
coordinate system	Yes	No	No	No
reference system	Yes	No	No	No

As nouns, coordinate system and reference system are synonyms defined as:

coordinate system and reference system: a system that uses coordinates to establish position

Other synonyms of coordinate system include frame of reference, reference frame.

coordinate system (noun)	reference system (noun)
a system that uses coordinates to establish position	a system that uses coordinates to establish position