arms vs ammunition

arms and ammunition both are nouns.

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

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

Other hyponyms of arms include ammo, armament, bomb, defence system, defense system, gunnery, hardware, naval weaponry.

arms (noun)	ammunition (noun)
weapons considered collectively	projectiles to be fired from a gun
the official symbols of a family, state, etc.	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