Nevus generally refers to pigmented nevus, and the difference between nevus and melanoma includes the nature, etiology, symptoms and treatment. 1. Nature: pigmented nevus is benign proliferation of melanocytes, which generally will not affect the health; melanoma is a tumor derived from malignant transformation of melanocytes, which has a higher degree of malignancy and may endanger human health. 2. Causes: The causes of nevus pigmentosus are mostly related to heredity, trauma and immunosuppression, etc. Melanoma may be caused by DNA damage and excessive exposure to ultraviolet rays. 3. Symptoms: Nevus pigmentosus manifests as spots, papules and patches of different sizes on the skin, with a diameter of less than 6mm and clear boundaries; melanoma has an asymmetric shape, irregular edges and a large diameter of more than 6mm, and it may also have symptoms such as hemorrhage, itchiness and ulceration. 4. Treatment: pigmented nevus generally does not need to be treated, if it affects aesthetics, it can be removed by laser treatment or surgical excision; early melanoma patients can be cured by surgical excision, and if it is not suitable for surgical treatment, it is necessary to orally consume Vimofenib or inject drugs such as Dacarbazine and Fumonisidine, which can help improve the symptoms of the tumor. The difference between pigmented nevus and melanoma is not unique, and it is recommended to consult a doctor at a regular hospital to learn about the matter. Medications need to be used as prescribed by the doctor.