Yes, there is a difference between the two! While some RDs may call themselves “nutritionists,” please be aware that not all nutritionists are Registered Dietitians. The definition and requirements for the term “nutritionist” vary. Some states, such as Pennsylvania, have licensure laws that define the range of practice for someone using the designation “nutritionist.“ In other states, however, virtually anyone can call themselves a “nutritionist,” regardless of education or training.