The main difference between a bong and a water pipe is the shape and size. Bongs are typically tall and slender, while water pipes are typically shorter and wider. Bongs also use water to filter smoke, while water pipes use air to filter smoke. Bongs cool the smoke before inhalation, making it smoother and easier on the lungs. Water pipes, on the other hand, do not cool the smoke, making it harsher to inhale. Additionally, bong water can be flavored, while this isn't possible with water pipes. Bongs are usually made of either glass, ceramic, or plastic, while water pipes are usually made of glass, ceramic, or metal. The materials used to make each type of device also affects the way smoke tastes, with glass and ceramic offering the best flavor, and metal and plastic having a more metallic taste. Overall, the main difference between a bong and a water pipe is the shape, size, and materials used. Additionally, bongs cool and filter smoke using water, while water pipes use air to filter and cool the smoke.