“Ceramic” or non-porcelain tiles are generally made from red or white clay fired in a kiln. They are almost always finished with a durable glaze which carries the color and pattern. These tiles are used in both wall tile and floor tile applications, are softer and easier to cut than porcelain, and usually carry a PEI 0 to 3 rating. Non-porcelain ceramic tiles are usually suitable for very light to moderate traffic and generally have a relatively high water absorption rating making them less frost resistant and they are more prone to wear and chipping than porcelain tiles.
Porcelain tile is a tile that is generally made by the dust pressed method from porcelain clays which result in a tile that is dense, impervious, fine grained and smooth, with a sharply formed face. Porcelain tiles usually have a much lower water absorption rate (less than 0.5%) than non-porcelain tiles making them frost resistant or frost-proof. Glazed porcelain tiles are much harder and more wear and damage resistant than non-porcelain ceramic tiles, making them suitable for any application from light traffic to the heaviest residential and light commercial traffic. Full body porcelain tiles carry the color and pattern through the entire thickness of the tile making them virtually impervious to wear and are suitable for any application from residential to the highest traffic commercial or industrial applications. Porcelain tiles are available in matte, unglazed or a high polished finish.

Thinset is a type of blended portland cement used to set tile on a slab or cementboard.  The term "thin" is from the thin bed that the tile is set in. Thinset mortar is a blend of portland cement, finely graded sand and a water retention compound that allows the cement to hydrate.  There are many different types of thinset available in grey and white colour, such as,  multi purpose, polymer modified, non-modified, fast setting or high quality latex modified thinset mortars.
Grout is used to fill the joints in between the tile.  There are different types of grout available such as portland cement based grouts and epoxy-based grouts.
The portland cement based is the most popular and is made up of graded sand, portland cement, sometimes water retentive additives, and colored pigments.

If properly installed, tiled flooring can last a lifetime. The only reason to replace the tiles would be if the look of the tile is no longer in style but this is only on an aesthetic basis.