roller vs platen

roller and platen both are nouns.

Word	Noun	Adjective	Verb	Adverb
roller	Yes	No	No	No
platen	Yes	No	No	No

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

Other hyponyms of roller include garden roller, paint roller, sprocket, trundle.

roller (noun)	platen (noun)
a grounder that rolls along the infield	the roller on a typewriter against which the keys strike
Old World bird that tumbles or rolls in flight; related to kingfishers	the flat plate of a printing press that presses the paper against the type
pigeon that executes backward somersaults in flight or on the ground	work table of a machine tool
a cylinder that revolves
a mechanical device consisting of a cylindrical tube around which the hair is wound to curl it
a small wheel without spokes (as on a roller skate)
a long heavy sea wave as it advances towards the shore