Typically, floor tile has a thicker construction than shower tile in order to withstand furniture, appliances, bathroom fittings and fixtures and regular foot traffic. Most types of bathroom floor tiling also feature extra texture to reduce the risk of slip hazards.
Wall tiling is usually smoother, thinner and generally a lot more delicate. The nature of its make-up also means it is much slicker when wet, which explains why wall tiles are not recommended for underfoot installation within a shower enclosure.