React and ReactDOM are two separate libraries that are often used together in the development of web applications with React.
ReactDOM, on the other hand, is a library that provides an interface between React and the DOM (Document Object Model). The DOM is a tree-like structure that represents the HTML of a web page, and ReactDOM provides a set of functions that allow React components to be rendered to the DOM and updated efficiently.
In short, React is a library for building user interfaces, while ReactDOM is a library for interacting with the DOM and rendering React components to the web page. While they are often used together, they serve different purposes and can be used independently of each other.