eyelid vs protective fold

eyelid and protective fold both are nouns.

Word	Noun	Adjective	Verb	Adverb
eyelid	Yes	No	No	No
protective fold	Yes	No	No	No

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

eyelid: either of two folds of skin that can be moved to cover or open the eye
protective fold: a flap of tissue that protects what it covers

eyelid (noun)	protective fold (noun)
either of two folds of skin that can be moved to cover or open the eye	a flap of tissue that protects what it covers