What are the differences between AngularJS (angular 1.x) and Angular (Angular 2.x and beyond)?

AngularJS and Angular are both frameworks developed by Google for building web applications, but they differ significantly in their architecture, language, and capabilities. Here’s a detailed comparison based on the provided sources:

1. Architecture

• AngularJS: Implements a Model-View-Controller (MVC) architecture. This framework divides the application into three interconnected components, which helps to separate the internal representations of information from the ways that information is presented to and accepted from the user[1][2][3][4][5][6].
• Angular: Uses a component-based architecture, which is more modular. This architecture uses components as the primary means of UI construction, replacing the older concepts of controllers and directives found in AngularJS[1][2][3][4][5][6].

2. Programming Language

• AngularJS: Primarily uses JavaScript. It is suitable for developers already familiar with JavaScript but does not enforce any strict programming paradigms[1][2][3][4][5][6].
• Angular: Introduced TypeScript, a superset of JavaScript that includes static types. TypeScript helps in catching errors early and provides powerful tools for large-scale development[1][2][3][4][5][6].

3. Mobile Support

• AngularJS: Was not built with mobile support in mind, which limits its capabilities in mobile application development[1][2][3][4][5][6].
• Angular: Is designed with mobile-first approach in mind, offering better performance and more tools for mobile app developers[1][2][3][4][5][6].

4. Performance and Optimization

• AngularJS: Uses a digest cycle for change detection, which can become performance-intensive in complex applications[1][2][3][4][5][6].
• Angular: Implements a unidirectional data flow and change detection mechanism, which improves performance significantly. Angular also supports ahead-of-time (AOT) compilation, reducing the runtime load and startup ti...