posting vs show card

posting and show card both are nouns.

Word	Noun	Adjective	Verb	Adverb
posting	Yes	No	No	No
show card	Yes	No	No	No

As nouns, show card is a hyponym of posting; that is, show card is a word with a more specific, narrower meaning than posting:

Other hyponyms of posting include show bill, theatrical poster, flash card, flashcard.

posting (noun)	show card (noun)
the transmission of a letter	a poster advertising a show or play
a sign posted in a public place as an advertisement
(bookkeeping) a listing on the company's records