I have seen lately a concept of installing open web applications in Firefox and Google Chrome just like extensions here .

While the site says it as a installable websites. It looks very similar to bookmarks to me. When you click either bookmarks or this installed applications, it opens new tab and the site or application can be viewed.

My question is what is the main difference between normal web application like Gmail, or Super user or Facebook and these installable websites? Also what is the advantage in using this installable web apps from normal web applications which we can access by entering url in the browser address bar?

I hope this is the right place to post this question. If not please guide me accordingly.