Scrum Master is the most misunderstood role and is entrusted with totally new duties when compared to the tasks traditionally performed by a project manager. There is no project manager in Scrum.
According to the Scrum Guide, a Scrum Master is “a facilitator for the team and the product owner. Rather than manage the team, the scrum masterworks to assist both the scrum team and the product owner.”
You can refer to this playlist https://www.youtube.com/watch?v=DbCvs-60ytM&list=PL9ooVrP1hQOF1nCUBIFxOSD80UYSsx4vq to know everything about Scrum Master.
The Scrum Master supports stakeholders by facilitating the work (which the PM also does), but, unlike the PM, he does not hold responsibility for the deliverable (the development team has) and for achieving the business objectives (which is the Product Owner)
The Project Manager is responsible for the entire project result.
To get a clarified view on how different project manger from scrum master, here you go https://www.youtube.com/watch?v=DbCvs-60ytM&list=PL9ooVrP1hQOF1nCUBIFxOSD80UYSsx4vq
Hope this helps!
Check out CSM Training to learn more about Scrum Master.