A retail xbox and a dev kit/debug kit are alot different.The mcpx is different.
The eprom is different,also on a dvt4 it has extra connectors,mostly for
dvd emulation.And when I used to have a dvt4 on the bottom of the
mobo it had a resistor.And on my debug kit there isn't one.
So its mainly hardware that separates a dev/debug kit from a retail.
And on the 360 dev kit.Just wait till the retail 360 is relashed.Then
you will see the dev kits floating around.