layer vs tier

layer and tier both are nouns.

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

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

Other hyponyms of layer include backing, mount, blanket, course, row, cushion, interlayer, lift, overlay, ply, wall.

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

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