SERP Left Rail
The Left Rail of the SERP is the left hand side on Desktop. The Left Rail contains Google's recommendations in the form of Bluelinks, Video Boxes, Image Boxes, Featured Snippets and other SERP Features.
SERP Right Rail
The Right Rail of the SERP is the right hand side on Desktop. The Right Rail contains the facts that Google has understood in the form of Knowledge Panels, Google Business Profiles, See results bout and People Also Search For.