It seems that the fundamental difference is the layout width. This is found at Dashboard > PageLines > Site Options > Layout Editor.
On the possibility of making that section full width, I think the problem is going to be your Site Design Mode. If using Full Width Sections, I think it may be possible, provided that the section we're trying to background is a full-width section. However, you're using, it seems, the content area for the first example, and in the second, the full-width sidebar.
Since you can't expand an area within the content area beyond its boundaries, I think the only way is going to be to use the full-width or universal sidebar to achieve this goal.