Most of the time when an app is updated, it's pretty clear what the update brings. New features? Enhancements and tweaks? Bug fixes? Whatever the case may be - it's right there in the changelog. However, there are those circumstances when that's just not the case. The recent update to HBO GO and MAX GO are a perfect example of this - especially the latter.
Why's that, you ask? Because both apps have the same changelog, which indicates "support for Jellybean 4.2" and "10-inch HD Tablets." Great. Except... not a single 10" tablet or Android 4.2 device that I've used is compatible with MAX GO, while everything under the sun is compatible with HBO GO (save for the OG, God rest its soul):
Left: MAX GO; Right: HBO GO
So, basically, there was an update that did something. Maybe you can catch some HD content from HBO now. Maybe not. But you probably won't be getting anything HD from MAX. Hopefully there will be an update that fixes this update.