An occupational therapy practitioner is commonly referred to as either a Registered Occupational Therapist (OTR) or a Certified Occupational Therapy Assistant (COTA), each a different level of practitioner. The 0TR has more extensive education and training in both breadth and depth than COTA, who works under the supervision of an OTR. Often the OTR is referred to as the "professional" level and the COTA is referred to as the "technical" level of practice.