What do you mean by "regular DS"? Phat/Lite or DSi?
As for WiFi, all support WEP.
But, only the DSi and 3DS have WPA, but that's only for their web browser and app store, since no DS games (save maybe for Black/White) have WPA encryption compatibility built into them.
As I just mentioned, DSi and 3DS have web browsers and 'app' stores.
Well, I should say the DSi does have both, and they were available day one on its release.
The 3DS, on the other hand, needs a system update to get those up and running, which hasn't been released yet.
And, cameras.
Phat/Lite have none. DSi has front and rear facing 2D camers. 3DS has a 3D camera and a 2d rear facing camera.