System Admin: Ability to change everything in the admin console. Also has the privileges of every admin/moderator setting below.
Space Admin: Can change the space settings via admin console. Also has privileges of those below.
User / Group Admin: User: Can add/delete users (not groups), etc via admin console. Group: Can add/delete groups (not users), etc via admin console. DO NOT have privileges of moderate content (below)
Moderate Content: Have the ability to delete, move, etc in the forums.