There is a major size difference and I can't find a detailed description on Debian website about the content of both .
Well, obviously the difference between the CD and the DVD is that the DVD image, being larger, holds a lot more packages :-).
For the exact list, see the FAQ:
If you just want a list of the files on a CD/DVD, look at the jigdo pages. There you can download all the .jigdo files used to create the images; they contain a list of the packages in the image. .jigdo files are simply compressed text files.