silver screen vs celluloid

silver screen and celluloid both are nouns.

Word	Noun	Adjective	Verb	Adverb
silver screen	Yes	No	No	No
celluloid	Yes	Yes	No	No

As nouns, celluloid is a hypernym of silver screen; that is, celluloid is a word with a broader meaning than silver screen:

Other hypernyms of silver screen include cinema, film.

silver screen (noun)	celluloid (noun)
a white or silvered surface where pictures can be projected for viewing	a medium that disseminates moving pictures
the film industry	highly flammable substance made from cellulose nitrate and camphor; used in e.g. motion-picture and X-ray film; its use has decreased with the development of nonflammable thermoplastics

silver screen (adjective)	celluloid (adjective)
	artificial as if portrayed in a film