Hi Marcio,
it's not the same. Creating UWP apps you use the Windows Runtime and .NET Core. The Windows Runtime can be used from native C++, JavaScript, and .NET callers (e.g. using C#). The types look like .NET types, but we just have the same metadata for the description. Open the Object Browser in Visual Studio and select the category "Windows". This shows the Windows.* namespaces that belong to the Windows Runtime.
Also, check this Wikipedia article:
https://en.wikipedia.org/wiki/Windows_Runtime
The Windows Runtime is already native. Creating UWP applications with .NET, the .NET code is also compiled to native code (when you publish the app to the store, and you can also select native code generation with the Visual Studio project settings). Here, you are using native runtime components - I think you've read about this in some articles. Can you supply links to these articles?
Hope this helps.
Cheers,