tier vs layer

tier and layer both are nouns.

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

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

Other hypernyms of tier include bed.

tier (noun)	layer (noun)
one of two or more layers one atop another	thin structure composed of a single thickness of cells
any one of two or more competitors who tie one another	a hen that lays eggs
a relative position or degree of value in a graded group	single thickness of usually some homogeneous substance
something that is used for tying	an abstract place usually conceived as having depth
a worker who ties something	a relatively thin sheetlike expanse or region lying over or under another

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