[routerLink] and routerLink are both used to link the routes from Html.
In [routerLink] we can provide the values dynamically whereas in routerLink we can't pass dynamic values.
[routerLink] Example
<a [routerLink] = [currentLink]>Back </a>
Component File
this.currentLink = 'home';
routerLink Example
<a routerLink = "home">Back </a>