There is nothing path breaking between angular 2 and angular 4 like angular 1 and angular 2. They are just doing it to maintain SEMVER(Sementic Versioning). Angular 2 is stable now so it would be better to prefer angular 2 instead of angular 4.
Angular 2 was a complete rewrite of AngularJS 1.x with many new concepts. Angular 4 however is the next version of Angular 2. The underlying concepts are still the same and if you have already learned Angular 2 you’re well prepared to switch to Angular 4 now.
The reason it’s Angular 4 and not Angular 3 is that the Angular Router package has already been in version 3 before. The Angular team would like to avoid confusion and decided to skip version 3 for Angular and continue with Version 4.
Update from comments
- Also, in Angular 4, animation functions are imported from
@angular/animationsinstead of@angular/core
For more detail i have published this article read here
- Why Angular4 over Angular2 ?