fireplace vs niche

fireplace and niche both are nouns.

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

As nouns, niche is a hypernym of fireplace; that is, niche is a word with a broader meaning than fireplace:

fireplace: an open recess in a wall at the base of a chimney where a fire can be built
niche: an enclosure that is set back or indented

Other hypernyms of fireplace include recess.

fireplace (noun)	niche (noun)
an open recess in a wall at the base of a chimney where a fire can be built	an enclosure that is set back or indented
	a small concavity
	a position particularly well suited to the person who or organization which occupies it
	(ecology) the status of an organism within its environment and community (affecting its survival as a species)