heat shield vs protective cover

heat shield and protective cover both are nouns.

Word	Noun	Adjective	Verb	Adverb
heat shield	Yes	No	No	No
protective cover	Yes	No	No	No

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

heat shield: a protective covering that protects a spacecraft from overheating on reentry
protective cover: a covering that is intend to protect from damage or injury

Other hypernyms of heat shield include protection, protective covering.

heat shield (noun)	protective cover (noun)
a protective covering that protects a spacecraft from overheating on reentry	a covering that is intend to protect from damage or injury