Watt
It is the unit of power
It conveys the amount of power that is required by a device
1 Watt = 1 Joule/ sec
kW * 1000 = Watts
Energy (kWh) = Power (kW) * Time (hour)
Joules is unit of energy or work
Joules is the energy dissipated as heat when a current of 1 Amp passes through a resister of 1 Ohm for 1sec