Ceramic tile is a broader term for a few subgroups of ceramics material, all of which are made from a mix of clay, sand, and other natural substances such as quartz. However, they all have different properties due to the way they are made, and how hot the kiln is when they are fired.
The hardest of the three ceramics, porcelain is often made with white clay, and is fired at 1200-1400 degrees Celsius. This extremely high heat increases the structural strength of the finished product, and makes the porcelain non-porous, smooth, and glassy.
Stoneware is also non-porous and smooth once it has been fired, and it is very hard to scratch. This makes it a popular choice for tableware and cooking implements, such as the crocks in slow cookers. It is also often used for decorative ceramic tile work.
The least durable ceramic, earthenware can also be referred to as terracotta or quarry tile, and is only fired at 900-1100 degrees Celsius. This leaves it porous and easily scratched which makes it unfit as a building material or kitchenware, but it is perfect for pottery. It is easy to form on a pottery wheel, and most home kilns can achieve the temperature required to fire it.
While not actual types of ceramic, glazed and mosaic tiles are often grouped in with the above varieties. Glazing is a glass-like gloss coat that waterproofs ceramic tile, and mosaic tiles are small, shaped tiles used to make a decorative piece. Glass, stone, and metal can also be mosaic tiles, not just ceramic.
This will give you a quick layman’s introduction to the different kinds of ceramic tile, and what they are popularly used for. This will hopefully make it easier for you to communicate with your tiling specialist about what kind of ceramic tile you may want and need for your project.