If you don't download something, how can you have it to run it offline? If a publisher doesn't put a file in a globally reachable location, how do others acquire it?
"Many installable web apps are hosted apps—normal websites with a bit of extra metadata. You can build and deploy hosted apps exactly as you would build and deploy any web app, using any server-side or client-side technologies you like. The only difference is that you must provide a small manifest file that describes the app.
If you want your app to work especially well offline or to be tightly integrated with the Google Chrome browser, you can create a packaged app. A packaged app is just a web app that the user downloads. Packaged apps have the option of using the Google Chrome Extension APIs, allowing packaged apps to change the way Chrome behaves or looks."
As mentioned previously, I unfortunately don't have the time to elaborate now, look for that blog post I mentioned within the next week or so to answer your question.
