Coffeescript classes vs Javascript extend

gistfile1.js

// All Backbone objects have the extend method built in.  
// This serves the same primary purpose as Coffeescript's extends keyword.  
// After all, they were actually written by the same person: Jeremey Ashkenas

// Coffeescript Implementation for Backbone Model
class Entities.User extends Backbone.Model
  defaults:
    firstName: "Brian"
    
  initialize: ->
    console.log @get("firstName")

// Javscript Implementation for Backbone Model
Entities.User = Backbone.Model.extend({
  defaults: {
    firstName: "Brian"
  },
  
  initialize: function(){
    console.log(this.get("firstName"));
  }
})

// Coffeescript Implementation for Marionette Views
class List.User extends Marionette.ItemView
  template: "path/to/template"
  tagName: "li"
  onRender: ->
    @$el.addClass "active"
  
class List.Users extends Marionette.CollectionView
  tagName: "ul"
  itemView: List.User

// Javascript Implementation for Marionette Views
List.User = Marionette.ItemView.extend({
  template: "path/to/template",
  tagName: "li",
  onRender: function(){
    this.$el.addClass("active")
  }
})

List.Users = Marionette.CollectionView.extend({
  tagName: "ul",
  itemView: List.User
})