The Service Account User Types are:
These users are members of your firm. They are automatically members of the Internal Users Group. Your firm is billed based on the number of Internal User accounts you purchase. These users are only added by a Repository Administrator.
These users may also be assigned as administrators, and may have some administrative functions delegated to them.
These are people outside your firm (auditors, outside counsel, etc) to whom you give access to a workspace or a set of folders for an extended period of time. These users can NOT be Administrators and generally have a reduced feature set. These users are also added on the Repository level by an Administrator.
ShareSpace Personal Contacts
These are also people outside your firm (such as a client). They are "guests" to your firm, and have access to a handful of documents over a short period of time via a ShareSpace. Each Internal User can create their own list of ShareSpace Contacts with whom they share documents with. ShareSpace Contacts are not added to your firm's repository by an Administrator, so they are often referred to as "non-repository users". These ShareSpace users can only have access to ShareSpaces (they cannot access folders or workspaces). However, both Internal and External users may also have access to a ShareSpace.
ShareSpaces are designed for ad hoc and secure document sharing. There are no subscription fees for any ShareSpace guest users who are granted access to a ShareSpace. ShareSpaces can be created, filed in folders within your Cabinet and can be created at anytime by users without requiring administrative help. ShareSpace guest users only see the contents of the ShareSpace to which they have access and do not see your organization's Cabinet structure.