The two biggest differences between Xamarin and Flutter are the languages used and the way the interface is rendered. In Xamarin, the user interface is implemented using XAML with C# support. In Flutter, both the logic and the entire user interface are handled by a modern, powerful language, Dart. Also an extremely important difference is the way the user interface is rendered. In Flutter, graphics and animations are drawn on the screen in real time using the Skia rendering engine. The Xamarin technology is slower because it has to translate the native control tree.