stopper vs stoppage

stopper and stoppage both are nouns.

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

As nouns, stoppage is a hypernym of stopper; that is, stoppage is a word with a broader meaning than stopper:

Other hypernyms of stopper include block, blockage, closure, occlusion, stop.

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

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