hole card vs playing card

hole card and playing card both are nouns.

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

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

hole card: (poker) a playing card dealt face down and not revealed until the showdown
playing card: one of a pack of cards that are used to play card games

hole card (noun)	playing card (noun)
(poker) a playing card dealt face down and not revealed until the showdown	one of a pack of cards that are used to play card games
any assets that are concealed until they can be used advantageously