Distinguish between drying agent and dehydrating agent.

Hint: Dehydrating agents mainly remove the water of crystallisation from the compound which is chemically bonded whereas the drying agent is used to remove the extra water present in the reaction mixture to get a dry product.

Complete solution
We know that drying agents can be defined as the substances which are used to dry a compound from the excess of water that is present with it. Also the dehydrating agents can be defined as the substances which are used to absorb water molecules which are present inside the lattice structure of a compound. Those water molecules are popularly known as the water of crystallisation.
The differences between drying agent the dehydrating agents are represented in the tabular form-


Note: To remove the water of crystallisation from the compound copper sulphate pentahydrate $(CuS{O_4}.5{H_2}O)$, in the chemistry laboratories during calorimetry, heating of the compound in a hot ceramic is done. Thus the blue colour of hydrated compound after dehydration changes to colourless in anhydrous compound.