post-horse vs post horse

post-horse and post horse both are nouns.

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

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

post-horse 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 post-horse include poster.

post-horse (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