finishing touch vs capstone

finishing touch and capstone both are nouns.

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

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

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

Other synonyms of finishing touch include copestone.

finishing touch (noun)	capstone (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