military advisor vs adviser

military advisor and adviser both are nouns.

Word	Noun	Adjective	Verb	Adverb
military advisor	Yes	No	No	No
adviser	Yes	No	No	No

As nouns, adviser is a hypernym of military advisor; that is, adviser is a word with a broader meaning than military advisor:

military advisor: a military officer who serves as an adviser to the troops of an allied nation
adviser: an expert who gives advice

Other hypernyms of military advisor include advisor, consultant, military officer, officer.

military advisor (noun)	adviser (noun)
a military officer who serves as an adviser to the troops of an allied nation	an expert who gives advice