Google've published a article to help you decide between building extensions and building apps for the upcoming Chrome Web Store. In the article, you'll read about how apps and extensions vary from the user's perspective and how they compare in their internal architecture and capabilities. Also included a deep dive on the concept of packaged apps as a blend of app and extension behaviour.
The new Chrome Web Store introduces the concept of installable web apps. These apps will live alongside extensions and themes in the store, which will become the one-stop shop for all three types of installable components. So what exactly are installable web apps and how do they differ from extensions?