poster vs post-horse

poster and post-horse both are nouns.

Word	Noun	Adjective	Verb	Adverb
poster	Yes	No	No	No
post-horse	Yes	No	No	No

As nouns, poster and post-horse are synonyms defined as:

poster and post-horse: a horse kept at an inn or post house for use by mail carriers or for rent to travelers

Other synonyms of poster include post horse.

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