I'm sure others can provide better technical descriptions of the unique differences but in my mind, documentation really helps guarantee the car is what it is and ensures the value. Anybody who has the "laundry list" can duplicate or forge VIN numbers, torque boxes, diff's, etc. The documentation is harder to forge and if you can contact previous owners that is even better. The documentation includes build sheets, original sale documentation, dealer service orders, registrations by various owners, etc.