this.nav.push("Page1") vs this.nav.push(Page1);

Ionic Framework ionic-v3
1

what’s the diffrence between using :
this.nav.push(“Page1”);
or
this.nav.push(Page1); & importing the page

what is better and why ?

2

I think this is a good place to start:
https://blog.ionicframework.com/ionic-and-lazy-loading-pt-1/