Besides @sdecandelario says (who i agree with), NativeScript provides a way to access directly to the iOS/Android API from JavaScript through reflexion. Instead React Native provides you a bridge to do this. I also can say React Native has a bigger community, a lot of support, even though it is just at version 0.40.
- Both are good options and though NativeScript provides you the option to use with TS/Angular 2 you can just write JavaScript as well.
- Other main difference is you use XML to design UI interfaces in NativeScript and JSX in React Native.
- Other thing is the goal from each framework, NativeScript aims to "Write once, run everywhere" meanwhile ReactNative aims to "Learns once, write everywhere", however in React Native you reuse a lot of code between iOS/Android.
Give a chance to each one and then make your choice.