commander in chief vs generalissimo

commander in chief and generalissimo both are nouns.

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

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

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

Other synonyms of commander in chief include commander-in-chief.

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