Myth: The Scrum Master is just another way of saying Project Manager
Not only do both roles do completely different things, but generally a Project Manager has a hierarchical role above the team, something that is not true of a Scrum Master.
Myth: The Scrum Master is the leader of the Scrum Team
The Scrum Master is not a Project Manager and does not have a higher role than the Scrum Team than the rest of the team. This is a common myth that can lead to disaster when adopting Scrum. It is human nature to look for someone to lead a group. Scrum teams are self-managed and decide how they are going to work and what rules (in addition to those imposed by Scrum) will be established.