What is the difference between power and energy?

power is measured in Watt (W) and represents the instantaneous power your device is consuming. energy is measured in kWh or Wh and indicates how much power is used over time. When you have a device is 1000 Watt and you leave it one for one whole hour you have used 1000 Wh or 1 kWh. Powercalc also uses this terminology to name your sensors. It creates a _power and _energy sensor by default.