The words "dietitian" and "nutritionist" get used interchangeably, but they do not mean the same thing, especially when it comes to training, credentials, and what a provider is qualified to do. If you are choosing who to trust with a medical condition, the difference matters.
A registered dietitian (RD or RDN) has completed an accredited degree, a supervised practice program of many hundreds of hours, passed a national board exam, and maintains continuing education. In Texas, dietitians can also be licensed (LD). This training qualifies them to provide medical nutrition therapy for conditions like diabetes, kidney disease, and GI disorders.
The title "nutritionist" is not consistently regulated the way "registered dietitian" is. Some people who use it hold advanced degrees and certifications; others have taken a short course. Because the term is broad, it does not tell you, on its own, what training the person has or whether they can safely manage a medical condition.
If you are managing a health condition, taking a GLP-1 medication, or want insurance to cover your visits, look for the RD or LD credential specifically. For general wellness coaching, other providers may be a fit, but always ask about training and scope before you start.