wild card vs playing card

wild card and playing card both are nouns.

Word	Noun	Adjective	Verb	Adverb
wild card	Yes	No	No	No
playing card	Yes	No	No	No

As nouns, playing card is a hypernym of wild card; that is, playing card is a word with a broader meaning than wild card:

wild card: a playing card whose value can be determined by the person who holds it
playing card: one of a pack of cards that are used to play card games

wild card (noun)	playing card (noun)
a playing card whose value can be determined by the person who holds it	one of a pack of cards that are used to play card games
an unpredictable factor