The size of the Android 4.4.2 update varies: on the Nexus 5, the update is about 54MB, while on the Nexus 7 tablet, the update is about 40MB. The Android 4.4.2 update brings system enhancements for the entire Nexus device range. Specifically, on the Nexus 7, the Android 4.4.2 system update claims to bring performance, stability and bug fixes.
On the other hand, the Nexus 5's Android 4.4.2 update notification surprisingly claims to bring camera improvements (faster shooting, less shutter lag and motion blur, more accurate focusing and exposures, better white balancing for true colours) and performance improvements and bug fixes.
This is surprising, as earlier this month, Google had announced the Android 4.4.1 update for the Nexus 5, which had primarily introduced camera enhancements for the smartphone. The Android 4.4.1 update brought camera improvements like faster focussing, particularly in low light situations; quicker white balancing for truer colours; ability to pinch-zoom the viewfinder in HDR+ mode and less shutter lag.
In November, almost two weeks after the release of the operating system, Google officially rolled out the Android 4.4 KitKat update for its Nexus 7 and Nexus 10 tablets.