Memory basically, that's the only difference
But there is that newer Xbox which is black as well. But it has a shiny case, built in wifi, more USB slots and allot more memory
EDIT: The new one is also more quiet
The new consoles also have only one cooling fan per unit, where as a normal Xbox has two. This is why the new models are quieter.
And some of the buttons on the console, like the power button, are touch sensitive.