The previous version introduced front-facing selfie flash (thanks to a full white display that flashes right before taking the shot), and this one comes with a few new features and changes, majority quite hard to notice. If the feature is active, users can see the lower third of the screen covered by a block of beige. Although, the feature doesn't offer automatic white-balancing like the iPhone's camera, but it's still a good option to brighten up your selfie. If you have a device which uses the Google Camera then you should be seeing the update live in the Play Store, and if it isn't showing up just yet it should be soon as it seems the update started hitting devices yesterday. Since most smartphones don't have a flash built in to the front-facing shooter, Google Camera mitigates this by adding a manila-toned slab right as your selfie is taken, which is supposed to help produce a little extra light in dimmer settings.
The double-tap to zoom function is a simple gesture that will zoom the camera to 50 per cent, and then zoom it out again, when users double-tap on the screen. As noted by Google, the latest version is created to work on recent Nexus and Pixel devices running Android 7.1.1 and above.