Hyperthyroidism, or hyperthyroidism for short, is a thyrotoxicosis caused by excessive production of thyroid hormones by the thyroid glands themselves. Hypothyroidism, or hypothyroidism for short, is a systemic hypometabolic syndrome caused by various causes of hypothyroid hormoneemia or thyroid hormone resistance. Their differences mainly include the following: 1. Etiology: the causes of hyperthyroidism include diffuse toxic goiter (Graves’ disease), nodular toxic goiter and autonomic high-functioning adenoma of the thyroid gland; the main causes of hypothyroidism include autoimmune damage (the most common cause is autoimmune thyroiditis, including Hashimoto’s thyroiditis, atrophic thyroiditis, postpartum thyroiditis, etc.), thyroid destruction, iodine overdose, and anti-thyroid drugs. 2. Clinical manifestations: The symptoms of hyperthyroidism include: hyperphagia, emaciation, fear of heat, excessive sweating, palpitations, agitation, irritability, insomnia, weakness, increased number of stools or diarrhea, protruding eyes, enlarged thyroid gland, and scanty menstruation in women. The main symptoms of hypothyroidism are: chilliness, weakness, swollen feeling in hands and feet, drowsiness, memory loss, less sweating, joint pain, weight gain, constipation, menstrual disorders in women, or excessive menstruation, infertility. 3.Treatment: Treatment of hyperthyroidism mainly includes anti-thyroid medication, 131I treatment, surgery and some other special treatments. Treatment for hypothyroidism mainly includes levothyroxine supplementation, management of subclinical hypothyroidism and treatment of mucinous edema coma. In summary, hyperthyroidism and hypothyroidism are two different diseases of the thyroid gland, and their differences mainly include the above three aspects.