Many Nutritionist are health- related experts. They tend to be complimentary practitioners and create tailor-made programmes of nutrition for the individual. They believe in holistic healing with one working on the causes that created the problem in the first place.
They can usually be found in health clinics, spas, etc, working with kinesiologists and other complimentary practitioners.
Many Dieticians work in hospitals, creating tailor-made diets for diabetics, weight loss; working out the calories in relation to health, etc.
Both fields are university trained nowadays and are quite skilled in BMI's, weight, and so on. The modern Nutritionists appears better able to understand neuro-physiology and the bodily systems from an energetic perspective and they have a great interest in the mitochondria and cell function.
Please note that all this is my own view and subjected to change.