Quality Control of India (QCI) had earlier only 4 levels of Yoga certifications - Level I, II, III and IV. But only two exams were used to be conducted for Levels I and II only. However, in the meantime, Yoga Certification Board has taken over QCI as Certification Authority for Yoga Professionals around June, 2019 and recreated new levels of Yoga Certifications. The following chart will give you glimpse of all categories of yoga certifications:

You can see that there are two hierarchies - First hierarchy relates to Yoga Education & Training and other one related to Yoga Therapy.
All the levels under each category has been given privilege of functions:
Yoga Education & Training
- Yoga Protocol Instructor - Yoga Instructors for teaching basics of yoga to teach common yoga protocol developed by the Ministry of Ayush for International Day of Yoga. For classes in parks, societies, for prevention of diseases and promotion of health.
- Yoga Wellness Instructor - Yoga Instructors to teach Yoga for prevention of illness and promotion of wellness in schools, yoga studios, work places, etc.
- Yoga Teachers & Evaluator - Master Trainers in Yoga educational Institutions, Yoga Training Courses and training programs. He or she can also act as Evaluator and assessor of Yoga Professionals. Can teach in studios, Institutions, colleges/ universities/ Institutions of higher Learning.
- Yoga Master - Shall act as Master Educator / Trainer in Yoga Educational programs & skilled professionals, can teach, evaluate & assess for all levels and will be a guiding force.
Yoga Therapy
- Assistant Yoga Therapist - Can work under supervision of certified physician or certified Yoga Therapist & Yoga Consultant on specific disorders
- Yoga Therapist - Can work alongwith certified physician or certified Yoga Consultant to give Yoga Therapy on all disorders.
- Therapeutic Yoga Consultant - Can practice Yoga for treatment of diseases in medical set up or independently. He should be a registered medical practitioner in any stream with Yoga Therapy.
Source: Website of Yoga Certification Board.