Mobile Apps

React Native is a JavaScript web framework that offers its own wrappers for native platform UI components while relying on Apache Cordova to provide the libraries necessary to interact with the underlying platform hardware. JavaScript as an interpreted language is dynamically and weakly typed. Dynamic typing means that objects can have multiple types. Weakly type means that types are coerced at run-time rather than enforced at compile time.

Xamarin is a C# framework that offers its own wrappers for all of the native platform APIs (including Apple Watch, tvOS, Android Wear, etc). C# as a compiled language is Statically and strongly typed. Static typing means that an object can only be one type. Strongly typed means that types are enforced at compile time. It’s also an Object Oriented Language.

One other difference that I’m surprised none of the other answers have brought up yet is that Xamarin can be further subdivided into 2 different approaches.