javascript - Using $onChanges vs $onInit in angular component -

is there difference between using controller1 vs controller2?

angular.module('app', []) .component('foo', {     templateurl: 'foo.html',     bindings: {         user: '<',     },     controller: controller1, //or controller2 });  function controller1(){     this.$oninit = function(){       this.user = angular.copy(this.user);     };      this.$onchanges = function(changes){       if(changes.user && !changes.user.isfirstchange()){         this.user = angular.copy(changes.user.currentvalue);       }     }; }   function controller2(){     this.$onchanges = function(changes){       if(changes.user){         this.user = angular.copy(changes.user.currentvalue);       }     }; } 

why should bother $oninit when can same in $onchanges , save rows?

is type of initialization better in $onchanges , $oninit better other kind of initialization?