There are two ways to deliver native iOS, Android, and Windows apps using Xamarin Technology
Traditional Xamarin approach: This approach can provide direct access to platform-specific API’s. And we can create platform specific apps such as using Xamarin.iOS for iOS applications, using Xamarin.Android we can create Android applications.
Xamarin.forms: This architecture is the same as that of traditional cross-platform apps. The most used method is to implement Portable Libraries or Shared Projects to save the shared code, and then create specific applications for each platform that will consume this shared code.