We created a demo for every available layout. They are supposed to give you an impression of how they look. The content of those pages is completly irrelevant.
Default theme - Floating content on background, full-width sticky-header
Centered-Submenu theme - Paged/floating content with submenu to the left
Centered theme - Content and Menu are max-width, background to right and left
Float-WideHeader theme - Paged/floating content with wide header
Fullscreen theme - Modules can use the full width to set backgrounds