poster vs show bill

poster and show bill both are nouns.

Word	Noun	Adjective	Verb	Adverb
poster	Yes	No	No	No
show bill	Yes	No	No	No

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

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

poster (noun)	show bill (noun)
a horse kept at an inn or post house for use by mail carriers or for rent to travelers	a poster advertising a show or play
a sign posted in a public place as an advertisement
someone who pastes up bills or placards on walls or billboards