Different ways to initialize AngularJS Controllers?

Question

I've been seeing these two ways to initialize controllers.

First Way:

app.controller('Ctrl', ['$scope', '$http', 'Api', function($scope, $http, Api) {}]);

Second Way:

app.controller('Ctrl', function($scope, $http, Api) {}]);

Are there any differences between these two? If not, which one is the "best practice"?