For personalized help in losing weight & solving health concerns, would I be better off looking for a Nutritionist vs Registered Dietitian?

Looking for help with losing weight, including any food sensitivities (that could cause bloating and/or headaches), with lowering cholesterol, with good nutrition for better health… those types of things. Someone who would do blood/urine tests for personalized analysis rather than just general diet advice. Would I be better off looking for a Nutritionist or a Registered Dietitian? Or another specialist?