Tell me the difference between bell's palsy and facial palsy?

Sub-set.: Bell's palsy is one type of facial palsy; there are many others. ("palsy" is an old term for paralysis.).

Both facial palsies: Bell's palsy is facial weakness or paralysis that is thought to be due to a viral infection of the facial nerve. There are other causes of facial palsy including tumor growth, stroke, infection and trauma to name a few.