Reactive Power in Inductor and Capacitor
Current leads voltage in a capacitor. Voltage leads current in an inductor. I was taught this using the CIVIL spelling:

In a C I leads V leads I in an L. (I hope that makes sense.)

The effect is that the voltage or current will be 180° out of phase between the inductor and the capacitor and so in summing them they tend to cancel out rather than add.


  As both of them store power then why the reactive power in them is not
  added instead of subtraction.


Both of them store energy but one will be maximum while the other is minimum. This effect is seen best in the resonant circuits where the energy flows back and forth between the inductive and capacitive elements.