The difference between multiple sclerosis and optic neuromyelitis optica includes disease definition, clinical symptoms, and treatment. 1. Disease definition: Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system, and optic neuromyelitis optica is an autoimmune disease mainly affecting the optic nerve and spinal cord. 2. Clinical symptoms: Multiple sclerosis can involve the brain, brainstem, cerebellum, etc. Common clinical symptoms include limb weakness, sensory abnormalities and ataxia. Optic neuromyelitis mainly manifests as optic neuritis and myelitis, such as vision loss, blurred vision, numbness and weakness of limbs. 3. Treatment: The treatment of multiple sclerosis is mainly symptomatic, such as fatigue can be treated with amantadine, modafinil, etc., and difficulty in walking can be improved with dalfampridine. Optic nerve myelitis mainly use glucocorticoid shock therapy, such as prednisone, methylprednisolone, etc., severe cases can be injected intravenously with high-dose immunoglobulin or plasma replacement, specific medication as prescribed by the doctor. These are some of the differences between the two diseases, the specific differential diagnosis need to consult a specialized doctor.