What difference between a kilovoltampere and kilovolt?

Kilo simply means 1000. Volt-ampere (VA) is a measure of power, similar to the watt. Volt is a measure of voltage, or electrical pressure. Voltage means electricity is available, but unless it is actually used, no current (amperes) flows, and no work (power) is done. Suppose you have a motor that needs 1000 volts to run, and when it is on it draws one ampere (amp) of current. We would say the motor supply voltage is one kilovolt. When the motor is running, we would say it uses one kilovolt-ampere (1KVA) of power (1 ampere * 1000 volts = 1000 VA or 1 KVA).