What is the Divi Library and why save or load an existing layout:
The Divi Library is place that stores pre-made layout templates as well as your custom saved layouts, modules and widgets (Divi > Divi Library).
Save a layout to the Divi Library if you would like to use it as a template for other posts or pages. This will cut down on the creation time needed for those future posts or pages.
To Load a Original/Saved Sections from your Divi Library:
This is a good option if you want reset your page and rebuild a demo page again (You have all demo page layouts in Divi Library).

- Click on the Insert Section icon

- Click on the Saved Section option.
- Choose the Section you want to import.
- Click on the Use This Section button.
To Save a Section in your Divi Library:
- Edit any page that contains a Divi Section and enable the Visual Builder
- Hover over the section you want to save to Divi Library.
- Click on the Save Section to Library icon

- Give the Section a descriptive name which will be used to identify the layout when loading it in the future.
- Click on the Save To Divi Library button.