army tank vs armoured vehicle

army tank and armoured vehicle both are nouns.

Word	Noun	Adjective	Verb	Adverb
army tank	Yes	No	No	No
armoured vehicle	Yes	No	No	No

As nouns, armoured vehicle is a hypernym of army tank; that is, armoured vehicle is a word with a broader meaning than army tank:

army tank: an enclosed armored military vehicle; has a cannon and moves on caterpillar treads
armoured vehicle: a vehicle that is protected by armor plate

Other hypernyms of army tank include armored vehicle, military vehicle, tracked vehicle.

army tank (noun)	armoured vehicle (noun)
an enclosed armored military vehicle; has a cannon and moves on caterpillar treads	a vehicle that is protected by armor plate