mucous membrane vs tissue layer

mucous membrane and tissue layer both are nouns.

Word	Noun	Adjective	Verb	Adverb
mucous membrane	Yes	No	No	No
tissue layer	Yes	No	No	No

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

mucous membrane: mucus-secreting membrane lining all body cavities or passages that communicate with the exterior
tissue layer: a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants

Other hypernyms of mucous membrane include membrane.

mucous membrane (noun)	tissue layer (noun)
mucus-secreting membrane lining all body cavities or passages that communicate with the exterior	a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants