A bridge connects two different interfaces similar to an adaptor. Unlike an adaptor however which is an adaption of two similar interfaces, a bridge is a connects two different interfaces.
A bridge pattern is typically applied when connecting various diverse items to a system in a similar way. For example, you may have 3 different printers and windows should know how to print on each of them. Windows makes the same API calls which are then "bridged" to the specific calls of each printer.