Android Wear 2 system features now updated via the Play Store for faster improvements
What's the difference? Well, before, you'd have to wait for an OTA update for your watch's operating system in order to enjoy a couple of extra features that the Google team decided to put in there. Now, said features can be added one by one as soon as the coders decide they are ready.
Not only that, Android Wear 2 users should already have their first batch of updates ready. These include 3rd party chat app support for Contacts, improved Play Store app discoverability, reduced accidental entries in the watch face menu, and various other minor feature updates and bug fixes.
It's a move similar to what phone manufacturers are doing — Sony, HTC, Samsung, and many others have their proprietary UI apps, like Calendar, Contacts, Camera, and so on, uploaded on the Play Store. You can't download said apps without owning a phone of the respective manufacturer, of course. Having said apps uploaded as separate entities on the Play Store means that the phone maker can update any one of them at any one time and does not need to worry about making a system update, clearing it with different mobile carriers, so on and so forth before pushing it.