Postgraduate is not a degree, but an education stage. When we finish the postgraduate course, we will get a master's degree. Moreover, postdoctoral is not a degree, but a teaching system, which aims to let doctors continue to engage in scientific research activities and improve their scientific research ability after obtaining their doctorate. Postdoctoral researchers are approved and registered in the Office of the National Postdoctoral Management Committee. They are engaged in postdoctoral research in mobile stations or workstations.