A crown, also referred to as a cap, is a dental restoration that covers the entire tooth and replaces the enamel on the outside with a new substance. In order to allow for correct chewing of food, crowns are shaped and proportioned to resemble natural teeth. They also come into normal contact with the opposing tooth.
On the other hand, a bridge is a fixed partial denture: it is glued to the teeth, it replaces some of the teeth, and it uses a fake tooth or teeth (denture) in the place of missing teeth. A bridge is used to replace one or more missing teeth, when functioning teeth are available on both sides of the missing tooth.