From e-Learning Documentation
Auditor - Identical to the student role but cannot receive a final grade for the course.
CE Student - Student role for continuing education or non-Registrar students.
Designer - Can add and edit course content but cannot interact with students or grade work.
Facilitator - Has all instructor permissions but does not show up in gradebook listed as instructor.
Grader - Can grade assignments, assessments, etc. but cannot access content or interact with students.
Guest Lecturer - Limited ability to add content and interact with students.
Instructor - Full permissions to read, revise, delete and add both content and participants to a site as well as interact with and grade students.
Observer - Can view all aspects of course content but cannot change content or interact with students.
Student - Can read content, participate in course activities, submit assignments and take tests/quizzes.
TA-NonGrading - Can edit content and update course but cannot access grading functions.
Teaching Assistant - Can add and edit most content in their sections as well as view, grade, and interact with students.