capstone vs finishing touch

capstone and finishing touch both are nouns.

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

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

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

Other synonyms of capstone include copestone.

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