armour vs shield

armour and shield both are nouns.

Word	Noun	Adjective	Verb	Adverb
armour	Yes	No	Yes	No
shield	Yes	No	Yes	No

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

armour (noun)	shield (noun)
tough more-or-less rigid protective covering of an animal or plant	hard outer covering or case of certain organisms such as arthropods and turtles
protective covering made of metal and used in combat	armor carried on the arm to intercept blows
a military unit consisting of armored fighting vehicles	a protective covering or structure

armour (verb)	shield (verb)
equip with armor	protect, hide, or conceal from danger or harm
	hold back a thought or feeling about