disc vs planchet

disc and planchet both are nouns.

Word	Noun	Adjective	Verb	Adverb
disc	Yes	No	No	No
planchet	Yes	No	No	No

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

disc (noun)	planchet (noun)
a flat circular plate	a flat metal disk ready for stamping as a coin
sound recording consisting of a disk with a continuous groove; used to reproduce music by rotating while a phonograph needle tracks in the groove
(computer science) a memory device consisting of a flat disk covered with a magnetic coating on which information is stored
something with a round shape resembling a flat circular plate