Glass is generally smoother than tile. This is due to the manufacturing process of glass, which involves melting and cooling the material to form a uniform, smooth surface. Tiles, on the other hand, are made by pressing clay or other materials into molds and then firing them, resulting in a textured surface. According to a study by the American Ceramic Society, the average surface roughness of ceramic tiles ranges from 0.5 to 1.5 micrometers, while glass surfaces typically have a roughness of less than 0.1 micrometers. This significant difference in surface smoothness makes glass a smoother material compared to tile.