An app will likely offer a better experience compared to a full or mobile site when on your phone, and when you close an Instant App, it is gone from your phone, although technically it will remain in your web cache until it is cleared out.
If you love the app, you can actually download the full installation by clicking "Install" in the top right-hand side of the Instant App.
For developers, it is a win-win. "It's the same Android APIs, the same source code, the same project," Android Instant Apps product management director Michael Siliski said. "In fact, it's taken some developers as little as a day to get up and running." Of course, the developers will have to work on editing the app so only necessary bits are downloaded for "Instant," but for some apps that will likely not be an issue given their low complexity. There is one restriction, however. All modules for Instant Apps must be 4MB or less, replicating an average web page.
Android users will start seeing Instant Apps later this year.
Source:
VB