say-so vs carte blanche

say-so and carte blanche both are nouns.

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

As nouns, carte blanche is a hyponym of say-so; that is, carte blanche is a word with a more specific, narrower meaning than say-so:

Other hyponyms of say-so include power of appointment, command, imperium, lordship, muscle, sovereignty.

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