No, they are NOT the same display! The LCD panel may be made by the same manufacturer, but its not the same display. Apple displays are 100% all digital, and have all the features mentioned above that the Dell displays do not have.
This is why Dell can sell a 20" LCD panel for $399 or whatever it is now days. Basically the Dell display like all of their products are made for consumers at a low price. This is also why the Dell display has both VGA and DVI along with USB 2.0 on it. Its a consumer display made for consumers with different needs. Apple displays are professional displays that are made to be hooked up to professional computers such as the PowerMac G5/MacPro, PowerBook G4/MacBook Pro. They are specifically designed to be ONLY digital, which is why they ONLY come with a DVI connector. This is also why they aren't marketed with the MacMini even though Apple hooks them up to a MacMini in their stores because they aren't consumer end displays.