Href is the basic attribute provided by Html to navigate through pages which reloads the page on click.
routerLink is the attribute provided by angular to navigate to different components without reloading the page.
Major difference between both is that href kills the state of the current page where routerLink doesnt lose the state of the page.
For Eg. if an input text box is present in the page, the routerLink will retains its value after navigation.The routerLink can be considered as the custom attribute of href in angular by overriding some of the features like Page reloading