retina vs membrane

retina and membrane both are nouns.

Word	Noun	Adjective	Verb	Adverb
retina	Yes	No	No	No
membrane	Yes	No	No	No

As nouns, membrane is a hypernym of retina; that is, membrane is a word with a broader meaning than retina:

retina: the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve
membrane: a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants

Other hypernyms of retina include tissue layer.

retina (noun)	membrane (noun)
the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve	a thin pliable sheet of material
	a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants