To make it short: none.
ECMAScript is Javascript. ECMAScript ist just the official name for it.
React and react native utilize Javascript or in other words: react is pure Javascript.
Regarding react/react native there is a exception though: JSX It's invented to sugarcoat the react methods to manipulate the VDOM and makes it more convinient. But that's a part of react/react native (and for some part vue.js likewise) and has nothing to do with the language Javascript itself.