The main difference between a WebApp and React Native is the use of native UI components instead of HTML. React Native uses the same building blocks for the UI as any native code would. So you get the look, feel and performance (UI-wise) of a native app, because the UI is native.
Why React native and not any other technology?
It gives us many solutions that other technologies cannot afford. Here is what you can do with React Native:
Building native mobile apps
Building cross platform mobile apps (iOS and Android)
Yeah, with React Native you can build mobile apps that can run on iOS and Android. This is one of the great benefits of React Native. Before Facebook created it, you had to build your app twice and with different code: one for iOS using Swift or Objective-C and one for Android using Java or Kotlin. React Native solved this problem so you can build your React Native app and it will work in iOS and Android.