Bronze Star Medal vs medallion

Bronze Star Medal and medallion both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bronze Star Medal	Yes	No	No	No
medallion	Yes	No	No	No

As nouns, medallion is a hypernym of Bronze Star Medal; that is, medallion is a word with a broader meaning than Bronze Star Medal:

Bronze Star Medal: a United States military decoration awarded for meritorious service (except in aerial flight)
medallion: an award for winning a championship or commemorating some other event

Other hypernyms of Bronze Star Medal include decoration, laurel wreath, medal, palm, ribbon.

Bronze Star Medal (noun)	medallion (noun)
a United States military decoration awarded for meritorious service (except in aerial flight)	an award for winning a championship or commemorating some other event
	an emblem indicating that a taxicab is registered
	a circular helping of food (especially a boneless cut of meat)
	a circular helping of food (especially a boneless cut of meat) "medallions of veal"
	any of various large ancient Greek coins