Ceramic tiles are any kiln-fired clay-based tiles. Porcelain tile is a specific type of ceramic tile. It is made from porcelain clay and is fired at extremely high temperatures. It is a very dense tile and virtually does not absorb water. Porcelain is the hardest and strongest commercial tile available. The average PEI rating of porcelain is 5.
Non-porcelain ceramic is made from various red and white clays. It does not need to be fired at as high a temperature, and is not as durable or moisture resistant as porcelain. The average PEI range of non-Porcelain tiles is 0-3.