* PhD (Doctor of Philosophy): This is a research doctoral degree awarded after completing years of advanced study and original research in a specific academic discipline. It focuses on contributing new knowledge to a field through scholarly research, writing a dissertation, and defending it. PhDs are generally not licensed to practice a profession in the same way MDs are; their expertise is in research and advanced knowledge within their chosen field. This field can be anything from the sciences (e.g., physics, biology, chemistry) to the humanities (e.g., history, literature, philosophy).
In short, an MD is a professional degree for practicing medicine, while a PhD is a research degree for conducting advanced scholarly work. While some individuals might hold both an MD and a PhD (often pursuing research within the medical field), they are distinct degrees with different purposes.