Instead of using the Fetch as Googlebot to just see an output of code and HTML, Google will show a visual representation of what Googlebot sees. It will also show you errors on what resources Googlebot was unable to access, preventing them from fetching and rendering everything on the page.
Here is the new “fetch and render” button on the Fetch as Google feature:
After you have a page to Fetch and Render, it will take a few minutes and show you a status complete indicator. The indicator may show “partial” rendering, if resources are being blocked from Googlebot’s crawl. Either way, clicking on it will show you the rendering results.
You also are able to specify the device type you want to fetch and render as, such as desktop, smartphone or other devices.
Here is how the desktop version may look, notice the crawl issues below. Also notice the tabs for both “fetching” and “rendering.”
Fetching shows you the code, HTML, etc, while rendering shows you the results as a web page visualization.