theatrical poster vs posting

theatrical poster and posting both are nouns.

Word	Noun	Adjective	Verb	Adverb
theatrical poster	Yes	No	No	No
posting	Yes	No	No	No

As nouns, posting is a hypernym of theatrical poster; that is, posting is a word with a broader meaning than theatrical poster:

Other hypernyms of theatrical poster include bill, card, notice, placard, poster.

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