commander-in-chief vs commander in chief

commander-in-chief and commander in chief both are nouns.

Word	Noun	Adjective	Verb	Adverb
commander-in-chief	Yes	No	No	No
commander in chief	Yes	No	No	No

As nouns, commander-in-chief and commander in chief are synonyms defined as:

commander-in-chief and commander in chief: the officer who holds the supreme command

Other synonyms of commander-in-chief include generalissimo.

commander-in-chief (noun)	commander in chief (noun)
the officer who holds the supreme command	the officer who holds the supreme command