Actually, porcelain and ceramic tile are the same. Both are part of the larger category of tiles we can call ceramic. They begin to diverge when we look closely at differences in hardness rating and porosity, and that's when we assign the purely ceramic or porcelain titles to them.
And certainly porcelain tile and ceramic tile are cousins when discussing other, wildly different types of tile such as terrazzo or stone. Both tiles are fired at high temperatures and both tiles are man-made (i.e., rather than a purely natural material that comes straight from the earth, such as slate).
Let's dig a little deeper at the differences between porcelain and ceramic tiles--before you make that huge investment (and irreversible installation) of tile in your kitchen, bathroom, or entryway.
Interior or Exterior: No Ceramic OutsideLaying ceramic tile outside would be disastrous. Ceramic is not even close to being durable enough for exterior use. If you live in areas which freeze, your tile would likely crack on the first freezing night. Porcelain tile can be laid outside, but stone is your best option.
Density: Porcelain Denser Than CeramicPorcelain clays are denser and thus less porous than ceramic clays. This makes porcelain tile harder and more impervious to moisture than ceramic tile.
Durability: Porcelain WinsNot only is porcelain tile more dense than ceramic tile, but due to its through-body composition it is considered more durable and better suited for heavy usage than ceramic tile. Chip the ceramic tile and you find a different color underneath the top glaze. Chip the porcelain and the color keeps on going--the chip is nearly invisible.
While both porcelain and ceramic are fired, porcelain is fired at higher temperatures for a longer time than ceramic. Also, porcelain has higher feldspar content, which makes it more durable.