This is both expected, yet odd. The Stock Android Gallery app, seen on Nexus devices, the Moto X, and the Google Play Edition Galaxy S4 and Google Play Edition HTC One is no more with the new Google Play devices introduced yesterday. The new devices, specifically, are the Sony Z Ultra Google Play Edition and the Google Play Edition LG G Pad 8.3.
The stock Gallery app, seen on every other device, is no more. This is surprising, since Google added some new editing features to the Gallery app on the Nexus 5. However, the Photos app was bundled with the device and with Android 4.4.1 the Camera app took you to Photos instead of to the Gallery.
It’s unknown if the Gallery app will stick around with older devices or if it will be phased out completely. If Google updates the Photos app with the same editing features that Gallery is currently capable of, then I wouldn’t be surprised if it does go away in a future system update.
Source: Android Central