These roles are often used in SharePoint deployments
Here is a break of the typical responsibilities:
Responsibilities: The Site Owner is formally responsible for the content of the site. He/she defines the overall purpose and need for the site, functional requirements (including components and layout), and makes high-level decisions about the site’s maintenance (such as closure/decommissioning of the site when no longer required). The Site Owner is also responsible for defining access permissions for the site, taking into account the need for collaboration as well as the potential sensitivity of the content involved.
Suggested person: The person within the organisation who is deemed responsible for the group/activity/function for which the site was created. Ideally a Manager (Team Leader or higher), Project Manager or Committee/Group member.
Responsibilities: The Site Moderator is responsible for the general administration of the site. Tasks may include: performing user management within the available security groups on approval of the Site Owner; resolving document check-out issues; maintaining the site’s folder structure; first-line contact person for site members; raising tickets in case of technical issues. The Site Moderator is not responsible for making decisions about the site’s content; these are responsibilities of the Site Owner.