mantelpiece vs mantlepiece

mantelpiece and mantlepiece both are nouns.

Word	Noun	Adjective	Verb	Adverb
mantelpiece	Yes	No	No	No
mantlepiece	Yes	No	No	No

As nouns, mantelpiece and mantlepiece are synonyms defined as:

mantelpiece and mantlepiece: shelf that projects from wall above fireplace

Other synonyms of mantelpiece include chimneypiece, mantel, mantle.

mantelpiece (noun)	mantlepiece (noun)
shelf that projects from wall above fireplace	shelf that projects from wall above fireplace