carte blanche vs say-so

carte blanche and say-so both are nouns.

Word	Noun	Adjective	Verb	Adverb
carte blanche	Yes	No	No	No
say-so	Yes	No	No	No

As nouns, say-so is a hypernym of carte blanche; that is, say-so is a word with a broader meaning than carte blanche:

Other hypernyms of carte blanche include authorisation, authority, authorization, dominance, potency.

carte blanche (noun)	say-so (noun)
complete freedom or authority to act	the power or right to give orders or make decisions
	an authoritative declaration
	one chap's arbitrary assertion