Hmm- both documents state that the used warranty does not replace or extend the new vehicle warranty's drive unit and battery warranty:
"The Tesla Used Vehicle Limited Warranty does not extend or otherwise alter the original NewVehicle Limited Warranty. The balance of the New Vehicle Limited Warranty, including the originalBattery and Drive Unit Limited Warranty, applies to used vehicles and overlaps with this LimitedWarranty."
So the dates on the website with respect to battery/drive unit warranty expiration must be wrong. THey should be 8 years from the original delivery date.