commanding officer vs commander

commanding officer and commander both are nouns.

Word	Noun	Adjective	Verb	Adverb
commanding officer	Yes	No	No	No
commander	Yes	No	No	No

As nouns, commanding officer and commander are synonyms defined as:

commanding officer and commander: an officer in command of a military unit

Other synonyms of commanding officer include commandant.

commanding officer (noun)	commander (noun)
an officer in command of a military unit	an officer in command of a military unit
	a commissioned naval officer who ranks above a lieutenant commander and below a captain
	an officer in the airforce
	someone in an official position of authority who can command or control others