The "before" version uses an older version of DayPilot that used inline styling (CssOnly="false" mode). The easiest way to get the same appearance is to replace the demo dll with the same version number of the full dll. However, you may miss the latest features this way.
The "after" version uses CSS-only styling using themes (it's the only option since version 8). The default theme is bundled (no need to include any additonal stylesheet) and looks like this:
http://www.daypilot.org/demo/Scheduler/
In your example, no styles are applied - it looks like there is a typo in the theme name (Theme/CssClassPrefix property) or the theme stylesheet (*.css) is not included in the page.
The DayPilot package includes a "traditional" theme that mimincs the original styling:
http://www.daypilot.org/demo/Scheduler/ThemeTraditional.aspx
In order to apply this theme, you need to include this stylesheet:
http://www.daypilot.org/demo/Themes/scheduler_traditional.css
and add Theme="scheduler_traditional" to the Scheduler tag:
<DayPilot:DayPilotScheduler ... Theme="scheduler_traditional" ... />