umm...
MBBS (Bachelor of Medicine, Bachelor of Science) is the european/english system of getting a medical degree so you start around 18 and go to med school for 6 years or so. thus, you don't go to 'college' or 'university'. instead you go to medical school. so an MBBS graduate is around 24 or 25 years old. they go into medical practice.
If you want to get a PhD, then you go to a university first (4 years), then to graduate school (4 or more years) and you get a PhD. This typically means a graduate is more 27 or 28 years old. and they tend to do reseach-related or teaching-related work.
in the US its different. most medical doctors go to a college/university first to get a bachelor's degree, then their medical degree (MD or DO), which is a fixed 4 years of school. then 3 to 8 years of residency. and they take care of patients for the most part. some medical doctors do reseach but they are very few. for the vast majority of them they end up doing patient care. the reasons for this are plenty. some of them being higher pay to do patient care, lifestyle, working with people and not having to write grants.
to get a PhD, you also go to college/university to get a bachelor's degree, then to graduate school which averages about 7 years. then anywhere from 2 to 10 years of postdoctoral training. and most people who have PhD do reseach or teach. some go to work for drug companies.
bottome line:
PhD = academic degree, therefore you are a specialist of something, you're trained to write, conduct experiments and do research. no training in patient care.
MD or DO = professional degree, you're trained to treat patients, no training in research
Hope that helps someone. anyone feel free to add to this.