reference system vs arrangement

reference system and arrangement both are nouns.

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

As nouns, arrangement is a hypernym of reference system; that is, arrangement is a word with a broader meaning than reference system:

Other hypernyms of reference system include organisation, organization, system.

reference system (noun)	arrangement (noun)
a system that uses coordinates to establish position	the act of arranging and adapting a piece of music
	the spatial property of the way in which something is placed
	an organized structure for arranging or classifying
	the thing arranged or agreed to
	a piece of music that has been adapted for performance by a particular set of voices or instruments
	an orderly grouping (of things or persons) considered as a unit; the result of arranging