Google announced some new added features to the Fetch as Googlebot tool in webmaster tools.
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.
In the crawl section of webmaster tools you will find a “Fetch”, submitting a URL with “Fetch and Render” will take a few minutes to show a status with indicator. After the indicator just click on the response to see the results. You can specify the device type you want to fetch and render as, like desktop, smartphone or other devices.
Fetching shows you the code, HTML, etc, while rendering shows you the results as a web page visualization.