Angular 4： Angular 4 是在 AngularJS 正式发布 5 年后推出的。 Angular 4 是一个基于 JavaScript 的开源框架，用于使用 JavaScript、HTML 和 TypeScript 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。
Angular 5： Angular 5 是 Angular 4 之后的 AngularJS 的更新版本，开发用于更快地创建应用程序，因为它删除了不必要的代码。 Angular 5 更先进，有自己的一套功能，如构建优化器、编译器改进和代码共享功能。它于2017年11月1日推出。
Angular 4 和 Angular 5 的区别：
| S.No. | Angular 4 | Angular 5 |
|---|---|---|
| 1. | Angular 4 was launched in the March 2017. | Angular 5 was launched in the November 2017. |
| 2. | Angular 4 supports earlier TypeScript versions such as TypeScript 2.2 and 2.1. | Angular 5 only supports TypeScript 2.5. |
| 3. | Angular 4 does not provide the option to restrict the unneeded white spaces, tabs and newlines. | While Angular 5 provides the option to restrict tabs, whitespaces and newlines. |
| 4. | Angular 4 does not have the feature of build optimizer. | Angular 5 has the feature of build optimizer. |
| 5. | Angular 4 does not provide support for multiple naming scheme. | Angular 5 provides support of multiple names for both directives and components. |
| 6. | In Angular 4, traditional approach is used for tracking life cycle events. | In Angular 5, developer can track the route of life cycle events with new router which provides a more realistic tracking. |