What's the difference between crowns and veneers?

Crowns cover all surfaces of a tooth, where the enamel of the tooth is located. At times it may extend below the enamel into the root area, if needed for support or to remove gum line decay. Once the outer layer of the tooth is reduced, a temporary crown is placed to protect the substructure and hold the position. A veneer is a thin covering on the face of the tooth. It may or may not cover the chewing edge of the tooth. Most will require a temporary. With a veneer, there is less tooth removed. Some veneers called "no prep" veneers require little  if any tooth reduction, no needles and no temporaries. Talk over the pros and cons with your dentist. Both are very successful, functional and natural looking. 

Crowns cover most of the tooth and veneers cover just the front part that you see. Crowns always involve removal of the outer layer of the tooth to make room for the crown material. Veneers need only the removal of a portion of the tooth that is necessary for the cosmetic result. Many times the tooth needs little to no preparation. Veneers are glued to the front of the tooth. Crowns are kept on by more of a friction fit with a cement like filler in the interface. 

A crown goes over your entire tooth (like a crown on a king's head!). A veneer only goes over the front of the tooth (think of a fake fingernail). They both will give your tooth an almost flawless appearance, but obviously, veneers are less involved.

Crowns will protect better (which is why root canaled teeth often get a crown, where veneers only protect the front. Both have merit - talk to your dentist to see what he or she recommends.

Veneers and crowns are different procedures.

It is necessary to have significant tooth structure present, preferably enamel, to place a veneer. Veneers are usually placed for cosmetic reasons and often must be placed on multiple teeth to achieve the desired effect and improvement. Veneers are not used to restore badly broken down teeth; in such cases crowns are indicated. 

Crowns usually involve greater preparation of the tooth, in addition to possible build-up of a badly broken down tooth. Crowns can be very esthetic when fabricated from porcelain or porcelain (or other tooth colored material) fused to metal. There are situations, most often in the back part of the mouth, when an all metal crown is used to minimize chance of porcelain fracture and wear of opposing tooth.