React JS is a JavaScript library used for building web applications, while React Native is a framework for building mobile applications using JavaScript and React. While React JS is designed for building web interfaces, React Native allows developers to build native mobile applications for iOS and Android using a similar component-based approach. This means that developers can reuse much of their React JS code when building mobile applications with React Native, but will also need to learn the specific platform differences and limitations. Overall, React JS and React Native are both powerful tools for building modern, dynamic applications, but they serve different purposes and require different skillsets.