The heater option eliminates the power strip and uses a bit bigger gauge extension cord type cord with just a single plug on the end. You'll run into tripping the power atrip if your heater is set on high, the cord eliminates that problem. But I've always been curious if the extra start up amp pulls of heaters on high would be enough to cause issues within the thermostat.
A seperate thermostat will NEVER work on a heater with anything digital.
You must always use an analog heater with a Ranco