Set
The number of separate heaters in the set, in other words, the number of seats that can be heated. On the market there are both single heaters and paired sets — usually designed for both front seats.
Power
Power consumption of the device. When choosing, this parameter often has an exclusively reference value: the energy consumption of heating systems is not so high as to cause problems when connected to the on-board network, and the specific heater power is selected by the manufacturer in such a way that the device is able to effectively perform its functions.