Ionic Framework 4 has a navigation component called Nav (<ion-nav>), which is, according to Ionic docs, intended for the users to
move between different pages in your app
This overlaps in functionality with built-in Angular router.
When is it better to use Ionic Nav component compared to built-in Angular router?
Essentially, if you want to dynamically load components without having them tightly coupled to the apps routing, you can use ion-nav. This should help keep the routing files clean.
A use case I can think of is a dynamic list of items leading to different child pages. This should be straightforward with ion-nav compared to angular-routing.
It works a bit like modals but while keeping the navigation behavior you expect when going between normal routes.
You can find a good explanation of its use cases in the docs here: https://beta.ionicframework.com/docs/api/nav/
