The SAFe Scrum Master is a credential that certifies individuals on the use of the Scaled Agile framework. It is offered by the Scaled Agile to professionals who have a minimum of five years of experience and demonstrate an understanding of Lean thinking and implementing the ART by passing the exam.
The Certified ScrumMaster (CSM) on the other hand is an entry-level credential offered by Scrum Alliance and is a good starting point for those who wish to start their career in Scrum and learn about Agile principles, roles, Scrum framework, values, artifacts, planning, organising, and executing.
Both credentials have a good standing in the industry and help professionals get good opportunities. What you choose to pursue depends on your previous experience and your future requirements. If you are SAFe experienced, then it is recommended that you go for the SSM credential.