What is the difference between a certified Scrum Master and a professional Scrum Master?

The difference between a Certified Scrum Master (CSM) and a Professional Scrum Master (PSM) is that CSM, given by the Scrum Alliance, covers basic Scrum concepts, targeting newcomers. It requires attending a two-day course and passing an exam. Conversely, PSM from Scrum.org is seen as more demanding, does not require specific courses, and includes three levels for seasoned Practitioners.