While Scrum Masters can be project managers and project managers can be Scrum Masters, the two terms cannot be used interchangeably. Project managers oversee the entirety of the project lifecycle, guiding teams and ensuring a smooth process as tasks are completed, whereas Scrum Masters are responsible for ensuring that teams are adhering to Scrum principles.  Scrum Masters are also only present within teams operating under the Scrum methodology, whereas project managers can operate within a wide variety of teams implementing any number of project management methodologies and frameworks.