Difference between passing arguments VS apply with arguments

Question

I have a backbone collection, that uses a save mixin to do a Bulk save (just a utility method since backbone does not natively support bulk save)

// Cars collection
define([
  'Car',
  'BulkSave'
], function(Car, BulkSave) {
     return Backbone.Collection.extend({
        model: Car,
        save: function() {
            var options = {
                ...
                onSuccess: function(cars) {
                    // do something with cars
                    console.log(cars);
                }
                ...
            };

            this.bulkSave(options);
        }
     }).mixin(BulkSave);
});
// BulkSave Mixin definition 

define([], function(){
    return {
        save: function(options){
            var thisCollection = this;

            $.ajax({
                type: options.type,
                url: options.url,
                dataType: 'json',
                contentType: 'application/json',
                data: JSON.stringify(options.data),
                success: function(data) {
                   // data would give me the list of cars
                   // that changed
                   options.onSuccess.apply(thisCollection, arguments); 
                }
            });
        }
    };
});

So when I want to a bulk save of the collection, I would be calling

cars.save();

The question I had here was in the success callback of the ajax method, I will be calling the onSuccess method available in the options object to which I will be passing in the arguments.

What is the different between

options.onSuccess(arguments);
// this logs an arrayList of 3 properties
// [0]  -- the actual list of cars which changed
// [1]  -- 'success'
// [2]  -- the xhr object

vs

options.onSuccess(thisCollection, arguments);
// When i do this instead 
// it logs
// the list of cars that changed instead

Can someone explain the difference between the 2 scenarios ?

Answer 1

In the first example you just pass the arguments object to that function.

In the second one, you invoke the function using apply. In short, the apply function calls the function with "spread" arguments. That means the your function is called like yourFunction(arg0 /* where arg is a single element from arguments */, arg1, argN, ...) with given "this". For more see the page I pointed out.