poster vs posting

poster and posting both are nouns.

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

As nouns, poster and posting are synonyms defined as:

Other synonyms of poster include bill, card, notice, placard.

poster (noun)	posting (noun)
a horse kept at an inn or post house for use by mail carriers or for rent to travelers	the transmission of a letter
a sign posted in a public place as an advertisement	a sign posted in a public place as an advertisement
someone who pastes up bills or placards on walls or billboards	(bookkeeping) a listing on the company's records