fetal membrane vs tissue layer

fetal membrane and tissue layer both are nouns.

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

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

fetal membrane: any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
tissue layer: a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants

Other hypernyms of fetal membrane include membrane.

fetal membrane (noun)	tissue layer (noun)
any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus	a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants