They are just sitting out there, out in the breeze, and they are located far from the coolant inlet to the pack.
If a Bolt and a Model 3 are parked out in the 2°F driveway for 48 hrs, both plugged in and topped up, what would the energy cost differences be for running these TMS systems?
In the AWD versions of the Model 3 and Y, the location of the motor, pumps, and Octovalve is really no further from the battery inlet than the heater and pump on the Bolt.
They have different battery chemistries, with different temperature requirements, so no simple answer is possible. Note that the 66 kWh battery in the Bolt is also a different chemistry, and apparently requires much less heating than the older 60 kWh chemistry.