disk vs planchet

disk and planchet both are nouns.

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

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

disk (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

disk (verb)	planchet (verb)
draw a harrow over (land)