stoppage vs stopper

stoppage and stopper both are nouns.

Word	Noun	Adjective	Verb	Adverb
stoppage	Yes	No	No	No
stopper	Yes	No	Yes	No

As nouns, stopper is a hyponym of stoppage; that is, stopper is a word with a more specific, narrower meaning than stoppage:

Other hyponyms of stoppage include breech closer, breechblock, plug, stopple, vapor lock, vapour lock.

stoppage (noun)	stopper (noun)
the act of stopping something	blockage consisting of an object designed to fill a hole tightly
an obstruction in a pipe or tube	(bridge) a playing card with a value sufficiently high to insure taking a trick in a particular suit
the state of inactivity following an interruption	an act so striking or impressive that the show must be delayed until the audience quiets down
	a remark to which there is no polite conversational reply

stoppage (verb)	stopper (verb)
	close or secure with or as if with a stopper