ace of diamonds vs ace

ace of diamonds and ace both are nouns.

Word	Noun	Adjective	Verb	Adverb
ace of diamonds	Yes	No	No	No
ace	Yes	Yes	Yes	No

As nouns, ace is a hypernym of ace of diamonds; that is, ace is a word with a broader meaning than ace of diamonds:

ace of diamonds (noun)	ace (noun)
the ace in the diamond suit	a serve that the receiver is unable to reach
	one of four playing cards in a deck having a single pip on its face
	someone who is dazzlingly skilled in any field
	the smallest whole number or a numeral representing this number

ace of diamonds (adjective)	ace (adjective)
	of the highest quality