The difference between saturated and unsaturated fats lies in their chemical structure. Saturated fats are composed of fatty acids with no double bonds between carbon atoms, making them solid at room temperature. Unsaturated fats, in contrast, contain one or more double bonds, resulting in a liquid state. Unsaturated fats are generally considered healthier, as they can improve cholesterol levels and reduce the risk of heart disease, while excessive saturated fat intake has been linked to various health issues.