1. as others mentioned its a fuller framework, mostly akin to using react with redux (or flux etc...) and a di framework. This also means that angular 2 third party components are probably easier to integrate.
2. Reactive Expressions, which angular2 uses in many places, is a joy to work with (though they might become maintenance hell later on I think). You can use RxJs with React of course, but it's easier when your framework is based on it
3. It uses string templates - which means that some things such as dynamic templates and per user customization of html would probably be much easier to do then in React.
4. It has Ionic - which is much much faster to develop for mobile with then react-native (though obviously there are important differences). It's unlikely that an Ionic like framework for react will gain traction with react-native to compete with.