A MOBILE APP built using React is a type of app that is developed using the React JavaScript library. React is a popular choice for building mobile apps because of its ability to create reusable UI components, which can be easily manipulated and updated in response to user interactions and changes in the data.

React Native is a framework that allows developers to build mobile apps using React. It allows developers to use the same codebase for both iOS and Android platforms, making it a cross-platform development tool. This means that developers can write the code once and then use it to build apps for both iOS and Android devices, which can save time and resources.

React Native uses native components, which means that the apps built with it will have a native look and feel. It also allows developers to access the native APIs of the device, such as the camera, GPS, and more, which makes it possible to build apps with native-like functionality and performance.

React Native allows developers to build mobile apps using the same principles and techniques that they would use to build web apps using React. This makes it a good choice for developers who are already familiar with React and want to build mobile apps.