What is the difference between SLDS grid and lightning layout in Salesforce?

Hello Anjali,

The Salesforce Lightning Design System grid (SLDS grid), based on Flexbox, provides a flexible, mobile-first, device-agnostic scaffolding system. It has features to control alignment, order, flow, and gutters. It includes helper classes that you can use to alter the look and behavior of your grid, such as alignment, order, flow, and padding helpers.

Lightning Layout provides modules and configuration for great layout authoring experiences. It uses the Panels In-Place Editor (IPE) to enable a drag-and-drop experience when laying out pages. Layout utility classes will help you to achieve layouts found within the Salesforce Platform.

Thanks