Melamine and porcelain are two very different materials: one is manufactured from one of the oldest plastic ever created, and the other is created from a special clay. Both have widespread uses in construction and industrial work, but the two rarely meet except in two particular types of products, home dinnerware and whiteboards used in schools and office buildings.
Melamine is a plastic dating back to the 1800s. Essentially, it is made out of nitrogen, carbon and hydrogen with a formaldehyde catalyst. When the mixture is exposed to heat it becomes a flexible plastic material. When it dries, it cools into a smooth surface that can easily be washed and used for a variety of projects.
Porcelain is made from clay that is heavy in mineral elements like feldspar. Manufacturers compress the clay into shapes and then bake it in a kiln. Porcelain is very heat resistant and extremely water resistant, making it ideal for both indoor and outdoor applications. Many types of porcelain are mixed with dyes that give them nearly as many colors as melamine, but porcelain also tends to be more expensive.
Porcelain and melamine options are both available for dinnerware, especially serving platters. The primary difference between the two--in addition to surface texture and weight--is their tolerance to heat. Most porcelain can be used safely in the microwave, while melamine cannot be microwaved or heated in the oven at all. There are concerns about the toxic properties of melamine, but this occurs only when the plastic is made into a powder and mixed with food, as has occurred with baby formulas produced in China.
When it comes to whiteboards, melamine is a more inexpensive option that coats a layer of pressboard with a white sheet of melamine that users can draw on with markers. Porcelain versions use a steel background and a white coat of porcelain. Although porcelain versions are much heavier, they are also made of durable metal and can be used to hold magnetic objects. Melamine boards are lighter, but are more sensitive to permanent markers and cannot hold magnets.
Porcelain is much more durable than melamine. In dinnerware, porcelain can sometimes crack or shatter under large amounts of force, but melamine can be dented more easily and needs to be replaced more often. On whiteboards, melamine layers wear through more quickly, leading to ghosting effects that eventually ruin the board. Porcelain lasts much longer in both cases.