ruling vs judicial decision

ruling and judicial decision both are nouns.

Word	Noun	Adjective	Verb	Adverb
ruling	Yes	Yes	No	No
judicial decision	Yes	No	No	No

As nouns, judicial decision is a hypernym of ruling; that is, judicial decision is a word with a broader meaning than ruling:

ruling: the reason for a court's judgment (as opposed to the decision itself)
judicial decision: (law) the determination by a court of competent jurisdiction on matters submitted to it

Other hypernyms of ruling include judgement, judgment.

ruling (noun)	judicial decision (noun)
the reason for a court's judgment (as opposed to the decision itself)	(law) the determination by a court of competent jurisdiction on matters submitted to it

ruling (adjective)	judicial decision (adjective)
exercising power or authority