crown jewels vs regalia

crown jewels and regalia both are nouns.

Word	Noun	Adjective	Verb	Adverb
crown jewels	Yes	No	No	No
regalia	Yes	No	No	No

As nouns, regalia is a hypernym of crown jewels; that is, regalia is a word with a broader meaning than crown jewels:

crown jewels: regalia (jewelry and other paraphernalia) worn by a sovereign on state occasions
regalia: paraphernalia indicative of royalty (or other high office)

crown jewels (noun)	regalia (noun)
regalia (jewelry and other paraphernalia) worn by a sovereign on state occasions	paraphernalia indicative of royalty (or other high office)
	especially fine or decorative clothing