This isn't true. The CD version also adds some extra interstitial videos. You can tell these when the game suddenly plays a pre-rendered video (like when you enter cyberspace). There may be other changes, but this is I think this is one of those times where the CD version was an afterthought, rather than the original intent.
EDIT: Ok, I've played more of the CD version. There's extra graphics on the NY City map when you click a location, too. There's probably more.
One of the most irksome things about the voice audio added for the CD version (aside from the occasionally questionable acting) is that you're not told who you're talking to. With the sound set to OFF (which turns on subtitles, like the FDD version had) you can see the character name above their dialogue... which is actually really important for the game. Otherwise I don't know how you're supposed to know who you're talking to. Hmm!
If you double right-click on characters you can examine them, which tells you who they are.
Still better to play the FDD version first IMO since the voice acting is sometimes impossible to understand.