Wearable apps run directly on the wearable device and in this way let you access the device's hardware, activities, and services all on the device itself. The breadth of operations that may be performed on a wearable device is limited by design, owing to the smaller scale and the need to efficiently manage processing power and memory. In addition to that, wearables don't support the Google Play store. In addition to that, Android Wear 1.x does not allow direct install of apps from the Google Play Store.
A companion handheld app addresses these concerns to let us benefit from a rich user experience on our wearable device. The point to remember is that a wearable app is packaged within a companion handheld app. The companion app is what gets published to the Google Play store, as described in the following figure:
When users download the companion app to a handheld device, the wearable app within it is automatically pushed to all connected wearables, as described...