optical disc vs DVD

optical disc and DVD both are nouns.

Word	Noun	Adjective	Verb	Adverb
optical disc	Yes	No	No	No
DVD	Yes	No	No	No

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

optical disc: a disk coated with plastic that can store digital data as tiny pits etched in the surface; is read with a laser that scans the surface
DVD: a digital recording (as of a movie) on an optical disk that can be played on a computer or a television set

Other hyponyms of optical disc include CD, compact disc, compact disk, videodisc, videodisk.

optical disc (noun)	DVD (noun)
a disk coated with plastic that can store digital data as tiny pits etched in the surface; is read with a laser that scans the surface	a digital recording (as of a movie) on an optical disk that can be played on a computer or a television set