fireplace vs hearth

fireplace and hearth both are nouns.

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

As nouns, fireplace and hearth are synonyms defined as:

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

Other synonyms of fireplace include open fireplace.

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)