1. 角 4 ：
Angular 4 是在 AngularJS 正式发布 7 年后推出的。它是一个开源和基于 JavaScript 的框架，用于在 JavaScript、html 和 TypeScript 中构建 Web 应用程序，TypeScript 是 JavaScript 的超集。 Angular 4 于 2017 年 3 月推出，支持较早的 TypeScript 版本，例如 TypeScript 2.2 和 2.1。
2. ReactJS：
ReactJS 是一个声明性、动态和可扩展的 JavaScript 库，用于构建应用程序的前端或用户界面。它是一个开源的、基于组件的前端库，只负责Web应用和移动应用的视图层。它由 Facebook 提供和管理。
Angular 4 和 ReactJS 的区别：
| S.No. | Angular 4 | ReactJS |
|---|---|---|
| 1. | It was developed by Google. | It was developed by Facebook. |
| 2. | It is a complete framework. | It is a JavaScript based library. |
| 3. | It is written using TypeScript. | It is written in JavaScript. |
| 4. | It works using browser’s DOM. | It works using Virtual DOM i.e., simplified version of DOM. |
| 5. | The number of developers using Angular 4 is more as compared to ReactJS. | The number of developer using ReactJS is less. |
| 6. | It provides two-way data binding. | It provides one-way data binding. |
| 7. | It is generally suited for building cross-platform mobile apps ,enterprise web applications and single page applications(SPA) too. | It is used for dynamic and single page applications. |
| 8. | It is difficult for beginners to learn Angular 4, even after knowing JavaScript. | It is simpler and easier to learn ReactJS for beginners who knows JavaScript. |
| 9. | Angular 4 is slow in performance in case of small or single page application. | While it is far better in performance in case of small or single page application as compare to Angular 4. |