Silver Star vs medallion

Silver Star and medallion both are nouns.

Word	Noun	Adjective	Verb	Adverb
Silver Star	Yes	No	No	No
medallion	Yes	No	No	No

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

Silver Star: a United States military decoration for gallantry in action
medallion: an award for winning a championship or commemorating some other event

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

Silver Star (noun)	medallion (noun)
a United States military decoration for gallantry in action	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