canister vs ammunition

canister and ammunition both are nouns.

Word	Noun	Adjective	Verb	Adverb
canister	Yes	No	No	No
ammunition	Yes	No	No	No

As nouns, ammunition is a hypernym of canister; that is, ammunition is a word with a broader meaning than canister:

canister: a metallic cylinder packed with shot and used as ammunition in a firearm
ammunition: projectiles to be fired from a gun

Other hypernyms of canister include ammo.

canister (noun)	ammunition (noun)
metal container for storing dry foods such as tea or flour	projectiles to be fired from a gun
a metallic cylinder packed with shot and used as ammunition in a firearm	information that can be used to attack or defend a claim or argument or viewpoint
	any nuclear or chemical or biological material that can be used as a weapon of mass destruction