obstruction vs stoppage

obstruction and stoppage both are nouns.

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

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

obstruction (noun)	stoppage (noun)
getting in someone's way	the act of stopping something
the act of obstructing	an obstruction in a pipe or tube
any structure that makes progress difficult	the state of inactivity following an interruption
something immaterial that stands in the way and must be circumvented or surmounted
the physical condition of blocking or filling a passage with an obstruction