layer vs exosphere

layer and exosphere both are nouns.

Word	Noun	Adjective	Verb	Adverb
layer	Yes	No	Yes	No
exosphere	Yes	No	No	No

As nouns, exosphere is a hyponym of layer; that is, exosphere is a word with a more specific, narrower meaning than layer:

layer: a relatively thin sheetlike expanse or region lying over or under another
exosphere: the outermost atmospheric layer

layer (noun)	exosphere (noun)
thin structure composed of a single thickness of cells	the outermost atmospheric layer
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

layer (verb)	exosphere (verb)
make or form a layer