The difference between patent foramen ovale and atrial septal defect lies in the following aspects. First, in terms of pathogenesis, foramen ovale is not closed because of inadequate nutrition and slow development. In contrast, atrial septal defect is caused by some genetic mutations, exposure to radiation and hair dyes in early pregnancy, and the use of certain drugs that are harmful to fetal development in early pregnancy. In terms of clinical manifestations, there is no clinical manifestation of oval foramen ovale, and there can be no symptoms in mild cases of atrial septal defect, but there can be clinical manifestations of chest tightness, chest pain, palpitation, shortness of breath and other discomfort in severe cases. In terms of treatment, foramen ovale may not need treatment, while for atrial septal defect, it needs to be given to improve cardiac function, or even require surgery.