DVD vs videodisk

DVD and videodisk both are nouns.

Word	Noun	Adjective	Verb	Adverb
DVD	Yes	No	No	No
videodisk	Yes	No	No	No

As nouns, DVD and videodisk are synonyms defined as:

DVD and videodisk: a digital recording (as of a movie) on an optical disk that can be played on a computer or a television set

Other synonyms of DVD include videodisc.

DVD (noun)	videodisk (noun)
a digital recording (as of a movie) on an optical disk that can be played on a computer or a television set	a digital recording (as of a movie) on an optical disk that can be played on a computer or a television set