open fireplace vs hearth

open fireplace and hearth both are nouns.

Word	Noun	Adjective	Verb	Adverb
open fireplace	Yes	No	No	No
hearth	Yes	No	No	No

As nouns, open fireplace and hearth are synonyms defined as:

open fireplace and hearth: an open recess in a wall at the base of a chimney where a fire can be built

Other synonyms of open fireplace include fireplace.

open fireplace (noun)	hearth (noun)
an open recess in a wall at the base of a chimney where a fire can be built	home symbolized as a part of the fireplace
	an open recess in a wall at the base of a chimney where a fire can be built
	an area near a fireplace (usually paved and extending out into a room)