Generally speaking,
Assistant professor: junior professor. A position usually obtained after obtaining a doctorate and/or completing postdoctoral research. After 4-8 years, assistant professors will be employed for life or expelled from the university.
Associate Professor: An intermediate professor, usually a tenured professor.
Professor (sometimes called "full professor"): Senior tenured professor.
Distinguished professor/donated chair (such as "John Smith Professor of Physics"): An honorary position in which the salary of a full professor is increased by linking it with donations from universities, private individuals, companies or foundations.
Assistant professor is the starting point, and you can become an assistant professor by getting a doctorate or completing postdoctoral research. Higher than an assistant professor. In China, we are called an associate professor. At present, there are many associate professors in China, but once they are rated as associate professors in the United States, they are basically employed for life (as far as I know, this is the Harvard system). Associate professor was promoted to professor again. Generally speaking, the director level of a department is higher than that of subordinates, and he is often a full professor or an associate professor. Honorary professor XXX is awarded according to different universities. Simply put, professors are better!
For example, the director of anesthesiology at Aso General Hospital of Harvard Medical School is very good, so what appears on the resume is
Jenny Weiner-Cronish, MD
Chief anesthesiologist; Henry Isaiah Dorr, Professor of Anesthesiology at Harvard Medical School (Henry Isaiah Dorr, this title means that she has made outstanding achievements and contributions, equivalent to distinguished professor/Donor Chairman).