ace vs ace of diamonds

ace and ace of diamonds both are nouns.

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

As nouns, ace of diamonds is a hyponym of ace; that is, ace of diamonds is a word with a more specific, narrower meaning than ace:

Other hyponyms of ace include ace of clubs, ace of hearts, ace of spades.

ace (noun)	ace of diamonds (noun)
a serve that the receiver is unable to reach	the ace in the diamond suit
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 (adjective)	ace of diamonds (adjective)
of the highest quality