armor vs protective cover

armor and protective cover both are nouns.

Word	Noun	Adjective	Verb	Adverb
armor	Yes	No	Yes	No
protective cover	Yes	No	No	No

As nouns, protective cover is a hypernym of armor; that is, protective cover is a word with a broader meaning than armor:

armor: protective covering made of metal and used in combat
protective cover: a covering that is intend to protect from damage or injury

Other hypernyms of armor include protection, protective covering.

armor (noun)	protective cover (noun)
tough more-or-less rigid protective covering of an animal or plant	a covering that is intend to protect from damage or injury
protective covering made of metal and used in combat
a military unit consisting of armored fighting vehicles

armor (verb)	protective cover (verb)
equip with armor