The difference between acids and bases lies in their chemical properties and behavior in water. Acids donate protons (H⁺ ions) to solutions, resulting in a lower pH, while bases accept protons, leading to a higher pH. Additionally, acids typically taste sour and can corrode metals, whereas bases taste bitter and feel slippery. The pH scale measures the acidity or basicity of aqueous solutions, with neutral substances having a pH of around 7, acids less than 7, and bases above 7.