Instructor: full access to the course site; can participate in the course as a student via Student Preview
Teaching Assistant: same level of access as instructors but excluded from communications directed at instructors in particular (such as the "email all instructors" tool in a classic style course site)
Course Builder: access is limited to tools for adding and organizing course content; cannot view or participate in course activities, including discussion
Grader: access is limited to grade center and student submissions; no access to adding and organizing tools
Facilitator: privileges related to course materials, gradebook, calendar, announcements, discussions, and groups
Student: full participants in the course site but cannot create new course items or view other participants' grades