coordinate system vs reference frame

coordinate system and reference frame both are nouns.

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

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

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

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

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