Here's why:

* Freezing Point Depression: Both salt and sugar lower the freezing point of water. This means that a solution of salt or sugar will freeze at a lower temperature than pure water.

* Salt's Effect: Salt is an ionic compound that dissociates into ions (Na+ and Cl-) when dissolved in water. These ions interfere with the formation of ice crystals, making it harder for the water to freeze.

* Sugar's Effect: Sugar is a molecular compound that doesn't dissociate into ions. It lowers the freezing point of water primarily by disrupting the hydrogen bonding between water molecules.

In summary:

* Salt water has a greater freezing point depression than sugar water because it produces ions that disrupt the ice crystal formation.

* This means that salt water will take longer to freeze than sugar water at the same temperature.