Difference between delegate.BeginInvoke and using ThreadPool threads in C#

In C# is there any difference between using a delegate to do some work asynchronously (calling BeginInvoke()) and using a ThreadPool thread as shown below

public void asynchronousWork(object num)
    {
        //asynchronous work to be done
        Console.WriteLine(num);
    }

 public void test()
    {
        Action<object> myCustomDelegate = this.asynchronousWork;
        int x = 7;

        //Using Delegate
        myCustomDelegate.BeginInvoke(7, null, null);

        //Using Threadpool
        ThreadPool.QueueUserWorkItem(new WaitCallback(asynchronousWork), 7);
        Thread.Sleep(2000);
    }

Edit:
BeginInvoke makes sure that a thread from the thread pool is used to execute the asynchronous code , so is there any difference?