Here is a brief description about it:
Super Users: These are the power users and has access to everything including Global Configuration.
Administrator: These are the admins who can access all the features of the website, excluding the Global Configuration.
Chapter Member: This group contains the chapter members, and the users can login to the website, register for events, etc.
Event Organizer: This group has access to everything related to the Events Management System.
Newsletter: This group has access to everything related to the Newsletter Management System.