Dear Student ,
KW is a unit of energy equal to 1,000 watt-hours, or 3.6 megajoules. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.
whereas
KWH is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour. One watt is equal to 1 J/s. One kilowatt-hour is 3.6 megajoules, which is the amount of energy converted if work is done at an average rate of one thousand watts for one hour.
Regards