refrigeration system vs cooling

refrigeration system and cooling both are nouns.

Word	Noun	Adjective	Verb	Adverb
refrigeration system	Yes	No	No	No
cooling	Yes	No	No	No

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

refrigeration system: a cooling system for chilling or freezing (usually for preservative purposes)
cooling: a mechanism for keeping something cool

Other hypernyms of refrigeration system include cooling system.

refrigeration system (noun)	cooling (noun)
a cooling system for chilling or freezing (usually for preservative purposes)	a mechanism for keeping something cool
	the process of becoming cooler; a falling temperature