Bleaching is the process of gradually altering the shade of natural teeth to a lighter color. This treatment is for teeth with few, if any, front fillings present and where the natural alignment of the teeth is generally pleasing from the onset because bleaching does not alter the size, shape or angulation of teeth. Dentists prefer the gradual bleaching of teeth at home with custom bleaching trays and FDA "safe" bleaches dispensed by your dentist rather than the "quicky" bleaches that are sold in retail stores because the acidity of the later products leave the teeth pitted and sensitive. Bleaching requires retreatment periodically to retain the desired lightness since teeth naturally darken with time.
Veneers are thin, laboratory produced shells of porcelain that are fabricated to fit over the fronts of the anterior teeth. Because they do not cover the whole tooth such as crowns do, this treatment is best for teeth that are generally strong but require a reshaping as well as whitening. Teeth that require strengthening as well as cosmetics are best treated with crowns. Very little, if any, of the tooth is drilled for this proceedure and, unlike bleaching, retreating to maintain color is not necessary.