artillery vs ordnance

artillery and ordnance both are nouns.

Word	Noun	Adjective	Verb	Adverb
artillery	Yes	No	No	No
ordnance	Yes	No	No	No

As nouns, artillery and ordnance are synonyms defined as:

Other synonyms of artillery include gun, heavy weapon.

artillery (noun)	ordnance (noun)
large but transportable armament	military supplies
a means of persuading or arguing	large but transportable armament
an army unit that uses big guns