Purple Heart vs medal

Purple Heart and medal both are nouns.

Word	Noun	Adjective	Verb	Adverb
Purple Heart	Yes	No	No	No
medal	Yes	No	No	No

As nouns, medal is a hypernym of Purple Heart; that is, medal is a word with a broader meaning than Purple Heart:

Purple Heart: a United States military decoration awarded to any member of the armed forces who is wounded in action
medal: an award for winning a championship or commemorating some other event

Other hypernyms of Purple Heart include decoration, laurel wreath, medallion, palm, ribbon.

Purple Heart (noun)	medal (noun)
a United States military decoration awarded to any member of the armed forces who is wounded in action	an award for winning a championship or commemorating some other event