Acute appendicitis and chronic appendicitis are different in terms of etiology, clinical manifestations, and treatment. 1. Etiology: (1) Acute appendicitis: the most common etiology is fecaliths in the appendiceal lumen, foreign body obstruction, resulting in significant proliferation of appendiceal lymphoid follicles, leading to acute inflammatory infection of the appendix. (2) Chronic appendicitis: Most of the cases are transformed from acute. The main lesions are different degrees of fibrosis of the appendix wall and inflammatory cell infiltration. 2. Clinical manifestations: (1) Acute appendicitis: typical epigastric pain with gradual transfer to the umbilicus, confined to the right lower abdomen after a few hours, and rarely causing pain in the left lower abdomen. Early onset of the disease may be accompanied by nausea, vomiting, anorexia and other symptoms and rapid heart rate, fever, malaise and other symptoms of systemic toxicity. (2) Chronic appendicitis: there is often pain in the right lower abdomen and limited pressure pain in the appendix, some patients only have vague pain or discomfort, strenuous activities or dietary disorders can trigger an acute attack. 3.Treatment: (1) Acute appendicitis: in most cases, appendectomy should be performed as soon as possible after diagnosis. Those who do not accept surgery or have contraindications to surgery can be treated with intravenous antibiotics such as levofloxacin and ceftriaxone sodium. (2) Chronic appendicitis: Surgical removal of the appendix is required after diagnosis. There are many differences between acute appendicitis and chronic appendicitis, but regardless of whether it is acute or chronic, it should be diagnosed and treated in a professional hospital in time.