A question I get a lot is what's the difference between a Dietitian and a nutritionist? It's a good one; there's often a difference in price and insurance coverage, so it totally matters to clients. The difference boils down to regulation, Dietitians are registered by a regulatory body while nutritionists are not.
But what does that mean? It means that to become a Registered Dietitian, and to be allowed to use that title (including RD), one must have completed an accredited university degree, then a 1 year internship that is also accredited. The degree is called different things at different universities (mine was called applied human nutrition), but includes a strong science basis, and classes on business, counselling and all aspects of nutrition through the life cycle. The internships often are based out of hospitals, and are quite rigorous; rotations in clinical, community and administrative nutrition are included. It's been quite a number of years since I wrote my registration exam, but I remember it being stressful; a lot of study went into that thing!
Those who use the title nutritionist may or may not have formal nutrition training. There are some, such as registered holistic nutritionists and certified nutrition practitioners who have completed a college course, however these may be through private colleges, and these vary in length and rigor. There are some nutritionists who know what they're talking about and can give some appropriate and useful information, however there are some who do not.
Because of the difference in training, seeing a Registered Dietitian will cost more. You are paying for the expertise you will get. RD's are trained to examine current scientific research and are able to apply it to your specific situation. This is why insurance companies often cover RD services and not nutritionists. It can seem like it's not worth it, but the old adage is true, you get what you pay for. Your health is not worth messing with, if you're going to be putting the work in to reach your nutritional goals, why not work with the experts?