showcase vs display case

showcase and display case both are nouns.

Word	Noun	Adjective	Verb	Adverb
showcase	Yes	No	No	No
display case	Yes	No	No	No

As nouns, showcase and display case are synonyms defined as:

showcase and display case: a glass container used to store and display items in a shop or museum or home

Other synonyms of showcase include case, vitrine.

showcase (noun)	display case (noun)
a glass container used to store and display items in a shop or museum or home	a glass container used to store and display items in a shop or museum or home
a setting in which something can be displayed to best effect