In SharePoint Online, roles can be split into Unit-Level Roles and Site-Level Roles or permissions.
Unit Level Roles
Site Network Administrator (SNA)
Site Network Administrators (SNA) are responsible for the structure, usage and permissions of their hubs and sites. They control their content and application creation, page layouts, navigation, libraries and folders. They can read, download, create and edit content and documentation. Site Network Administrators provide technical assistance.
Business Owner (BO)
The Business Owner is to help manage the University’s SharePoint Online. They oversee and are accountable for the content and use of SharePoint Online in their college, department or division.
Ideally this person is a senior administrator or Senior Management Team (SMT) member, but need not be a technical person, as they have no responsibilities within the system.
Their role is to ensure the business use of SharePoint Online in their unit is compliant, consistent, managed and supported, and to nominate a sufficiently skilled Site Network Administrator.
Site-Level Roles and Permissions
Hub Administrator
SharePoint Online hub sites have a 'special' Administrative role that allows them to associate sites with a hub. Normally this role is reserved for SNAs but can also be delegated to other trusted SharePoint users in a unit. This is a separate permission to Site Administrator but in general, hub administrators are also made site administrators of the hub site.
Site Administrator
The Site Administrator (also known as the Site Collection Administrator) has the highest level of access in a SharePoint site. In the new flat architecture model, the Site Administration role / permission can be delegated by the SNA to someone else. To clarify, the SNA will not automatically become a site administrator if - for example - the holder ot the SNA role changes after someone leaves or steps down. Site Administrators are the delegated technical leads in their individual sites.
Site Owner
Site Owners have a high level role / permission level that has access to all the site contents and can also control site permissions as well as access, edit and create new content. It is a step down from the Site Administrator but is still a powerful role that again can differ from the Site Administrator or the SNA.
Site Member
Site Members have read / write access to content in a site. Normally this is a content creation role with the ability to create new lists and libraries, and other site content.
Site Visitor
Site visitors usually have 'read / download' access to content in a site. Normally site visitors can browse site contents to navigate around a site, but may be 'locked out' of sensitive areas in a SharePoint site where appropriate.
