The Galaxy Watch 4 is the first one of Samsung's smartwatches to be running the Wear platform - an OS that both Samsung and Google have collaborated on. Yes, rather than the Samsung smartwatch running Google's WearOS, the company are going to bring the best of their worlds to this new OS. This was confirmed during Google's yearly I/O developer's conference.
What Samsung lacked in their original Tizen OS was that they couldn't generate the developed interest with the smartwatches. This was due to the fact that the app department with the smartwatches was pretty limited. Google was lacking a major OEM (Original Equipment Manufacturer) for smartwatches. An OEM with global brand recognition and access. Google itself had shown a lack of hardware innovation for their smartwatch platform (in some people's opinion).
While Google doesn't typically allow their OEMs to customise the look/feel of the Wear OS, Samsung will be allowed to add One UI on top.
More features that we know of now is the battery size of the new Samsung device. The latest SGS certification of the Galaxy Watch 4 has revealed information about its battery size. The SM-R860 and SM-R865F models of the Galaxy Watch 4 have now been certified. The listing reveals that this particular model, the 41mm variant of the Galaxy Watch 4, will have a 247mAh battery. It supports 5W charging.