React is a library because it provides functions and components you can use in your code. A library is a collection of code you can use in your project, but it doesn’t dictate how you structure your application or use the library. You can use React differently, from simple components on a page to complex single-page applications.

On the other hand, a framework provides a more prescriptive approach to building applications. A framework typically includes a set of rules, conventions, and patterns that you must follow to use it effectively.