coping stone vs copestone

coping stone and copestone both are nouns.

Word	Noun	Adjective	Verb	Adverb
coping stone	Yes	No	No	No
copestone	Yes	No	No	No

As nouns, coping stone and copestone are synonyms defined as:

coping stone and copestone: a stone that forms the top of wall or building

Other synonyms of coping stone include capstone, stretcher.

coping stone (noun)	copestone (noun)
a stone that forms the top of wall or building	a stone that forms the top of wall or building
	a final touch; a crowning achievement; a culmination