The difference between mouth ulcers and leukoplakia is manifested in the different nature of the disease and the different populations in which it is prevalent. Mouth ulcers are self-healing diseases that occur in a wide variety of people. White spots may be cancerous and are common in middle-aged men. Mouth ulcers most often occur in the lip and cheek mucosa or the tip of the tongue, with white pseudomembrane, the ulcer appears red, swollen, concave and painful, especially the pain is very obvious. However, ulcers can heal on their own, usually in about 14 days. White spots are white spots, flakes or stripes, which are found in middle-aged men, especially those who have a history of smoking, and there is a possibility of cancerous transformation of white spots. The differentiation between mouth ulcers and white spots needs to be identified in the stomatology department.