finishing touch vs copestone

finishing touch and copestone both are nouns.

Word	Noun	Adjective	Verb	Adverb
finishing touch	Yes	No	No	No
copestone	Yes	No	No	No

As nouns, finishing touch and copestone are synonyms defined as:

finishing touch and copestone: a final touch; a crowning achievement; a culmination

Other synonyms of finishing touch include capstone.

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