In OLE DB, what is the difference between an interface and an implementation?

An OLE DB interface is specified by a set of objects, and the properties and methods that they expose, and OLE DB defines standardized interfaces. An object need not expose all of its properties and methods in a given interface. An OLE DB implementation defines how the object supports the interface. The implementation is completely hidden from the user. Thus developers of an object are free to change the implementation whenever they want, but they should not change the interface without consulting their users.