What is the difference between "Werden-Passiv" and "Sein-Passiv"?

The so called "Werden-Passiv" is composed by the verb "werden" and the "Partizip 2" of the verb used. The only conjugated verb is the verb "werden". This form of passiv is used to express an action or a process.

On the other hand the "Sein-Passiv" is used to describe the result of an action, the static state (Zustand) of an object without implying any action or change. For this reason it is often called "Zustand-Passiv" . It is composed by the "Partizip 2" of the verb and by a conjugated form of the verb "sein".