OK, here's some basic and quick explanations:
This is a sort of Super Admin. Anyone in this group essentially has the highest power over forum settings. At first only Marcin (the CEO of Malwarebytes) had this authority, however others in the company have gained it as well (Robert and Ted have it since they manage the servers, and thus it is required for them to perform their jobs properly). Neither you nor I will ever be a Root Admin.
There are two groups for members of the security community that are trusted to assist in the Malware Removal section (Experts and Trusted Advisors). The Experts are people such as researchers and the various folks that assist in malware removal at UNITE and ASAP forums (these people usually have gone through training programs to earn this level of recognition). The Trusted Advisors are those who either don't have the same credentials as the Experts, or who do not commonly assist in malware removal at UNITE or ASAP forums, but who still have the technical knowledge to provide assistance with malware removal or with various other computer issues. If you wish to be in either of these groups, then you will most likely need to graduate from one of the UNITE schools. Note that the line between these groups can often be a bit thin, and I personally have been in both the Experts group and the Trusted Advisors group at various times.
These are users who are trusted by the admins to hunt down spam posts and users on these forums, and report them.
These are users who report malware to our research team, and have been granted access to download samples from our malware and rogue reporting forums. There are instructions in those forums for how to become a member of this group.
These are users who volunteer to maintain the various translations of Malwarebytes' Anti-Malware. Since Malwarebytes does not have employees who speak every language, they rely on volunteers to provide the translations for almost every language that Malwarebytes' Anti-Malware supports.
I would believe that these are people who are trusted to manage the Software Update forums. It may have some small moderation powers associated with it, but only with regards to the Software Update forums.