medallion vs emblem

medallion and emblem both are nouns.

Word	Noun	Adjective	Verb	Adverb
medallion	Yes	No	No	No
emblem	Yes	No	No	No

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

Other hypernyms of medallion include allegory.

medallion (noun)	emblem (noun)
an award for winning a championship or commemorating some other event	special design or visual object representing a quality, type, group, etc.
an emblem indicating that a taxicab is registered	a visible symbol representing an abstract idea
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