For my money, Robbie was the admin on this forum, has he really been replaced in that function? Take for example the requests to add or remove a sub-forum; no one here appears to genuinely be in a position to do so. Or if they are, they have been keeping quiet about it up to this point in time.
Admin: Manage the technical details required for running the site. Responsibilities include: to promote and demote members to/from moderators, manage the rules, create sections and sub-sections, as well as perform any database operations, such as database backup, etc., make forum-wide announcements, change the appearance, etc. May also act in the capacity of a morderator.
Moderator: Manage the day-to-day affairs of a forum or board. Have access to the posts and threads of all members for the purpose of moderating discussion, keep the forum clean, neutralizing spam and spambots, answer users' concerns and general questions, Common privileges include: ‘deleting, merging, moving, and splitting of posts and threads, locking, renaming, stickying of threads, banning, suspending, unsuspending, unbanning, warning the members, or adding, editing, removing the polls of threads.
The most basic way to understand this is to see it as a hierarchy, or a three-tier pyramid. The base of the pyramid or hierarchy is the users. They are abundant. Some of these users will be chosen to become the moderators, or some people from the outside will brought in to moderate. These moderators become the second tier of the pyramid, where they have to watch over and control the users. The admins are the top of the pyramid. They either own the group, have made the group, or have been assigned as the admin of the group. They basically have all the power in the group and are the authority figure. The watch over and control the moderators and the users.