Final answer:
An exothermic reaction has stronger bonds in the products while an endothermic reaction has weaker bonds in the products.
Step-by-step explanation:
An exothermic reaction occurs when the bonds in the products are stronger than the bonds in the reactants. This means that the energy of the products is lower than the energy of the reactants. On the other hand, an endothermic reaction occurs when the bonds in the products are weaker than those in the reactants.