c# - Place Usings inside or outside of namespace?

I was learning MVC WebAPI and I was following a tutorial and everything was going fine untill I saw the following:

namespace HelloWebAPI.Controllers
{
    using HelloWebAPI.Models;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Net;
    using System.Net.Http;
    using System.Web.Http;


    public class ProductsController : ApiController
    {}

What we usually do is that we add the resources\scope in the beginning like this:

using HelloWebAPI.Models;
using System;
using System.Collections.Generic;
using System.Linq;

using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace HelloWebAPI.Controllers
{

    public class ProductsController : ApiController
    {}

My supervisor told me that it is okay and it is supposed to be okay, because it is an official MS tutorial on the subject.

** What I want to know that why this doesn't matter, so that I have a better understanding about it? **

Answer

There is a difference, small but there is.

It's all about the sequence of name resolution made by compiler.
The good answer on subject you can find here:

Should Usings be inside or outside the namespace

In practise in first case compiler, in case could not find a type information immediately,
would search among namespaces declared inside using. In second case, instead, would search first among the actual namespace and after only go to search inside declared outside.