Mouth guards are similar to aligners that are fitted to your teeth, but in most cases they are made of more layers and are thicker to withstand higher forces and last longer.
Dental veneers are thin, custom-made dental restorations (shells) that are placed on the front of the teeth to improve their aesthetic appearance, color or shape.
They are usually made of ceramic or composite. Porcelain (ceramic) veneers are more durable and look more natural, while composite veneers are cheaper and quicker to produce.