Before we look at the specific Layouts on the Avada Restaurant prebuilt website, the first thing to understand is the Layouts and Layout Sections’ architecture. You can think of Layouts as a container for the page content. In contrast, the actual content comes from the various Layout Sections. There are four Layout Sections on a page – the Header, Page Title Bar, Content, and Footer Layout Sections.
There is a default Global Layout, and any Layout Sections added to that will be shown on all pages of your website. There are Conditional Layouts with conditional logic to determine how the Layout will be used.
You can make as many Layouts and Layout Sections as you like, and you can use the Layout Sections in multiple Layouts. But you can only use a specific condition on a single Layout, so the theme knows which one to use.
See Understanding Layouts & Layout Sections and Understanding Conditional Layouts for more info.