The client side advancement in web application using angular, made so many people to choose angular.The people thought of moving their application towards angular is because of its features like Cross platform,speed and performance,testing features,animation and productivity.We can also call is an Angular era.Angular helps to build modern applications using Mobile or Web or Desktop.
Angular 2 is completely different than Angularjs.The Angular team is advancing their features and releasing new angular version every year.
Angularjs is MVW framework whereas Angular2 is component based framework.
Seperation of HTML logic from application logic.(means HTML logic are written in templates and application logic is written components.