Enzymes are proteins that increase the rate of chemical reactions.
Substances that increase or decrease the rate of a chemical reaction but cannot add take place of reactants only provide a platform to the reacting substances are catalysts.
Biological catalysts are enzymes.
For reactions, catalysts lower the activation energy.
For a reaction, the lower the activation energy, the quicker the rate.
Thus, by reducing activation energy, enzymes speed up reactions.
In reactions, catalysts are not used, and reactions take a large time to complete.