Difference between ngRoute and ui-router

I am new to AngularJS. I find Angular quite interesting and planning to use angular in my big apps. So I am in the process to find out the right modules to use.

What is the difference between ngRoute (angular-route.js) and ui-router (angular-ui-router.js)modules?

In many articles when ngRoute is used, route is configured with $routeProvider. However, when used with ui-router, route is configured with $stateProvider and $urlRouterProvider.

This creates a bit of confusion for me. Which module should I use for better manageability and extensibility? Your answers are greatly appreciated.