The Links tab contains links labs can pass along to their photographers (on the lab's website or via email) to allow their photographers to signup for their lab's SimplePhoto service.
Lab Administrators can use the Photographers tab to easily navigate between photographer accounts inside their lab.
When a lab administrator enters a photographer account using the Photographers tab, they have the ability to access the Product Groups Authority feature in the Photographer Information settings page. This process is outlined in the Product Groups Authority help document.