The Therapist

A Registered Behavior Technician is like a nurse of the ABA world. They pass a exam and must have hands on training before beginning. However, they cannot do anything without the permission of the BCaBA or BCBA.
 

A Board Certified assistant Behavior Analyst is like the nurse practitioner of the ABA world. They have at a minimum a bachelors in ABA, a thousand hours of supervised fieldwork, and passed their board exam. They still must have supervision from a BCBA but can make in the moment decisions on cases, write plans, and conduct assessments.

A Board Certified Behavior Analyst is like the doctor of the ABA world. They have went to school and got their masters, had thousands of supervision hours, and passed the board exams. They make the final decisions about a case and train the RBT's and BCaBA's.