AngularJS: factory and share data between controllers

My question is AngularJS: Why people prefer factory to share data between controllers

i am new in angular. so trying to know how to share data between two controller and search google. i visited few pages and found most of the time people use factory to share data. i just like to know can't we do it by service instead of factory ?
1st example

"FirstCtrl">
"text" ng-model="data.firstName">
Input is : {{data.firstName}}

"SecondCtrl"

Input should also be here: {{data.firstName}}

myApp.factory('MyService', function(){

return {

data: {

firstName: '',

lastName: ''

update: function(first, last) {

// Improve this method as needed

this.data.firstName = first;

this.data.lastName = last;

}

};

});

// Your controller can use the service's update method

myApp.controller('SecondCtrl', function($scope, MyService){

$scope.data = MyService.data;

$scope.updateData = function(first, last) {

MyService.update(first, last);

}

});