blockage vs breechblock

blockage and breechblock both are nouns.

Word	Noun	Adjective	Verb	Adverb
blockage	Yes	No	No	No
breechblock	Yes	No	No	No

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

blockage: an obstruction in a pipe or tube
breechblock: a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing

Other hyponyms of blockage include breech closer, plug, stopper, stopple, vapor lock, vapour lock.

blockage (noun)	breechblock (noun)
the act of blocking	a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing
an obstruction in a pipe or tube
the physical condition of blocking or filling a passage with an obstruction