upper mantle vs layer

upper mantle and layer both are nouns.

Word	Noun	Adjective	Verb	Adverb
upper mantle	Yes	No	No	No
layer	Yes	No	Yes	No

As nouns, layer is a hypernym of upper mantle; that is, layer is a word with a broader meaning than upper mantle:

upper mantle: the upper part of the mantle
layer: a relatively thin sheetlike expanse or region lying over or under another

upper mantle (noun)	layer (noun)
the upper part of the mantle	thin structure composed of a single thickness of cells
	a hen that lays eggs
	single thickness of usually some homogeneous substance
	an abstract place usually conceived as having depth
	a relatively thin sheetlike expanse or region lying over or under another

upper mantle (verb)	layer (verb)
	make or form a layer