Why was Angular 3 skipped, and what are the major differences in Angular 4 beta

angular

I just noticed that the Angular 4 beta was released, but cannot find much info on it. I'm making an app in Angular 2 right now and am kind of scared that Angular 4 is what I should be using.

What are the differences? Why did the team skip Angular 3, or have I just been living under a rock?

Angular is being developed in a MonoRepo it means a single repo for everything. @angular/core, @angular/compiler, @angular/router etc are in the same repo and may have their own versions.
The advantage of MonoRepo is, you don’t have to deal with the versioning of the code dependencies.

Now the problem is with the @angular/router which is already in a 3.X version. And that’s because of some active and huge developments on the router section, like route-preload.
Now releasing Angular as version 3, with its router on version 4 will create confusion
To avoid this confusion they decided to skip the version 3 and release with version 4.0.0, so that every major dependency in the MonoRepo are on the right track.

Because they wanted to sync the angular version with the angular router version. Angular will have a new version release every six months but Angular 4 will be backwards compatible with Angular 2/ https://www.gurustop.net/newsletter/19