On Google search, suppose your search results include a file download. What do you do? You click on it and let it open with your computer's own viewer (ie pdf docs with Adobe reader). Now suppose that file is designed to exploit a hole or bug in that program. Then you're in trouble. Google has introduced a new feature that will render those files into html using Google Docs. So next time files appear in your google search (docs, powerpoint, pdf, etc) hit quick view instead of opening the files.
There's no difference (see below screenshots), and its safer and a tad faster too!
View with default PDF viewer (foxit):
View with google docs:
