Member
An organizational member does not have access to the organizational panel, so a member can not edit any settings of the organization.
A member can however create new projects in the organization.
Members can be added automatically to all new projects as a Contributor.
Administrator
An organizational administrator has access to the organizational panel, and can edit organizational settings and can add/remove members from the organization.
An administrator can also create new projects in the organization.
Administrator can be automatically added to all new projects as a Supervisor.