wing case vs elytron

wing case and elytron both are nouns.

Word	Noun	Adjective	Verb	Adverb
wing case	Yes	No	No	No
elytron	Yes	No	No	No

As nouns, wing case and elytron are synonyms defined as:

wing case and elytron: either of the horny front wings in beetles and some other insects which cover and protect the functional hind wings

wing case (noun)	elytron (noun)
either of the horny front wings in beetles and some other insects which cover and protect the functional hind wings	either of the horny front wings in beetles and some other insects which cover and protect the functional hind wings