Yes, you can put it that way. If a room is only used irregularly for short periods, you can create a perceived warmth with a heat radiator (infrared heater). However, this warmth only exists in the radiation area, not sideways, because the room remains largely cold. If a room is to be used permanently, it must really be heated, and that of course costs energy. A heating system does this faster than an infrared radiator, especially since they usually have much less heating capacity/power consumption.