generalissimo vs commander-in-chief

generalissimo and commander-in-chief both are nouns.

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

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

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

Other synonyms of generalissimo include commander in chief.

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