Droop of the face. Bell's palsy is a term for loss of function of the seventh facial nerve, the nerve that supplies the muscles of 1/2 of the face. It usually is of overnight onset, generally painless and felt to be due to inflammation of the nerve in its narrow exit canal from brain to face. It causes lid and mouth droop on one side. Most clear by six months; a few last and need surgical support.
Facial weakness. Bells palsy typically presents as weakness affecting all of one side of the face, leading to a drooping mouth, slurred speech, and a droopy eyelid. It can cause weakness of eyelid closure, requiring the patient to wear a patch to keep the eyelid closed and prevent the eye from drying out. If the forehead is spared, or if you have any symptoms elsewhere in the body, see an md to rule out stroke.