ngRoute is a angular core module which is good for basic scenarios. I believe that they will add more powerful features in upcoming releases.
URL: https://docs.angularjs.org/api/ngRoute
Ui-router is a contributed module which is overcome the problems of ngRoute. Mainly Nested/Complex views.
URL: https://github.com/angular-ui/ui-router
Some of the difference between ui-router and ngRoute:
