endocranium vs membrane

endocranium and membrane both are nouns.

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

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

endocranium: membrane lining the inside of the skull
membrane: a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants

Other hypernyms of endocranium include tissue layer.

endocranium (noun)	membrane (noun)
membrane lining the inside of the skull	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