But one big difference between Xwt and Xamarin Forms is that Xwt supports Linux via GTK (GTK1, GTK2 & GTK3) whereas Xamarin Forms does not.

Xamarin Forms also requires different code for different targets, such as:

   // Android
   Forms.Init(this, null);
   var androidFragment = new MyFormsPage().CreateFragment(this);
 
   // iOS
   Forms.Init()
   var iosViewController = new MyFormsPage().CreateViewController();
 
   // UWP
   Forms.Init(e);
   var uwpElement = new MyFormsPage().CreateFrameworkElement();