Remember that even though you will find ceramic floor tile with everything from a very shiny surface to a very rough surface, they are all glazed tiles and are therefore impenetrable by liquids. It usually has a light Grey colored bisque. The glazes on porcelain tile are often more vibrant than those of ceramic tile and they usually have a certain uniqueness from tile to tile. Some lines, though, will have the uniform look of ceramic grade tile. Porcelain tile is also frost-proof, so it can be used in swimming pools and fountains.
Unglazed porcelains are available in larger sizes for commercial flooring.
Porcelain will always be the most durable tile you can buy. They typically are earthtone colors of terracotta-reds, browns, and greys. They are perfect for patios and walkways as well as commercial floors where a non-slip surface is needed. It typically has a high polished surface. As with most stones, natural color variations are part of it's beauty.