Active Power or True Power:
It is given by P = VI cos θ Watt
It is the power, which is in fact consumed in any circuit. Its unit is Watt. The above formula indicates that the power attained by a load is not only the product of its rms values of its terminal voltage and current but includes an added multiplicative factor cos θ, called power factor of the load.
This is the power taken by the reactance and its unit is volt-amp reactive (VAr).
This is given by
Q = VI sin θ VAr
Q is called reactive power as it is linked with the reactive elements (LC) and does not contribute to the net transfer of energy from the source to the load.