Gastritis is an inflammatory response of the gastric mucosa to various irritants in the stomach; gastric ulcer is an inflammatory defect in the gastric mucosa. The difference mainly includes the following aspects: Etiology: common causes of acute gastritis include stress (such as severe trauma, surgery, mental stress, etc.), drugs (such as aspirin and other non-steroidal anti-inflammatory drugs), alcohol, etc. Common causes of chronic gastritis include Helicobacter pylori infection, duodenal-gastric reflux, drugs (NSAIDs) and toxins, autoimmunity, age, etc. Common etiologies of gastric ulcers are gastric acid and pepsin imbalance, Hp infection, drugs (e.g. long-term use of NSAIDs, glucocorticoids, clopidogrel, etc.), abnormal mucosal defense and repair, genetic susceptibility, etc. Clinical manifestations: Acute gastritis often has epigastric pain, fullness, nausea, vomiting and loss of appetite. In chronic gastritis, there are no obvious symptoms, and even if there are, they are mostly non-specific, such as discomfort in the upper and middle abdomen, fullness, dull pain, etc. They can also show indigestion symptoms such as acidity, belching and nausea. The typical symptom of gastric ulcer is epigastric pain, which can be dull, burning, distending, sharp, and hunger-like discomfort in nature. Characterized by a chronic process with recurrent or periodic attacks, some patients have rhythmic epigastric pain associated with meals, mostly postprandial, and the abdominal pain can be relieved by acid suppressants or antacids. Treatment: Gastritis and gastric ulcer treatment drugs mainly include gastric acid inhibitors, Hp eradication, gastric mucosal protective agents, but their specific medications are treated according to the cause and condition. Acute and chronic gastritis are mainly treated with medication. For severe precancerous lesions, submucosal dissection can be performed under gastroscopy. In addition to drug treatment, endoscopic treatment is available for ulcer bleeding, and surgical treatment is also considered in the following cases: ① when complicated peptic hemorrhage is ineffective by drug, gastroscopy and vascular intervention; ② acute perforation, chronic penetrating ulcer; ③ scarring pyloric obstruction, endoscopic treatment is ineffective; ④ gastric ulcer with cancer. Prognosis: Acute gastritis: most gastric mucosal erosions and bleeding can heal and hemostasis on their own, a few patients with mucosal erosions can develop into ulcers with increased complications, but usually respond well to drug therapy. Chronic gastritis: chronic non-atrophic gastritis has a good prognosis. Some chronic atrophic gastritis can be improved or reversed, mild heterogeneous hyperplasia can be reversed, and severe cases are prone to transformation into cancer. Gastric ulcer: effective drug treatment can greatly improve the healing rate of gastric ulcer, the death rate of gastric ulcer in young adult patients is close to zero, and elderly patients mainly die from serious complications, especially hemorrhage and acute perforation, the death rate is less than 1%. Therefore, gastritis and gastric ulcer can exist separately or simultaneously, and the difference between the two is mainly manifested in the above aspects, but the diagnosis is also based on gastroscopy.