Aplastic anemia and leukemia, both of which are diseases of the blood system, have distinct differences: I. The nature of these two diseases is different. Aplastic anemia is a bone marrow failure disease; leukemia is a malignant clonal proliferative disease of bone marrow. Secondly, the pathogenesis is different. Aplastic anemia is a bone marrow hematopoietic failure disease, in which the hematopoietic tissue in the bone marrow is severely reduced during bone marrow aspiration examination, while leukemia is a hematopoietic stem cell malignant clonal disease, in which leukemia cells proliferate in the bone marrow in a disorderly manner. Third, the clinical manifestations are different. Patients with aplastic anemia show symptoms of anemia, infection, and bleeding, while patients with leukemia show symptoms of anemia, infection, and bleeding, as well as symptoms of invasion of organs other than the bone marrow, such as enlarged liver, spleen, and lymph nodes. Fourth, the treatment methods are different. Aplastic anemia is mainly treated with immunosuppressive therapy and stimulation of hematopoiesis with cyclosporine, Conlivon, anti-lymphocyte globulin, etc. Patients with heavy or very heavy aplasia need to do allogeneic hematopoietic stem cell transplantation; while leukemia is mainly treated with chemotherapy, and patients with conditions can do hematopoietic stem cell transplantation.