Here is an overview of the most important user roles
This user has access to all functionalities. In addition to what the instructor can do, an admin can for example add users and control various settings.
This is the standard role. This is for all the users that are supposed to only have access to the course as a participant (front-end).
This user has access to the Simplylearn course editing capabilities. But, the instructor only has access to edit the courses that the Admin allows them to edit. Read more about this role here.
The group leader has access to the Simplylearn reporting tools. But they only have access to this for the groups they are leaders for. This role solves your problem when you want a user to only watch specific course participants. Read more about this role here.