What is the difference between middle ages doctors and todays?

Doctors in the Middle Ages had no real medical knowledge whatsoever. They needed a degree in Theology to practice, and knew a little of ancient Greek medicine, but they believed in (and treated accordingly) demons and miasmas as the cause of disease. The main "treatment" for just about everything was bloodletting to bleed out the demons. Obviously, many patients died from lack of blood making their real conditions worse. Doctors today base their practices on science instead of religion and superstition, and have the accumulated knowledge of all the past studies in medicine to look to for answers.