用下面的语句获得网页的源代码，和直接访问获得网页源代码不一样，是咋回事

用下面的语句获得网页的源代码，和直接访问获得网页源代码不一样，是怎么回事？
网页地址：http://finance.sina.com.cn/stock/message/sogusina/sogu600635.htm          


Dim   url   As   String   =   "http://finance.sina.com.cn/stock/message/sogusina/sogu600635.htm "   '   网页地址

                Dim   httpReq   As   System.Net.HttpWebRequest

                Dim   httpResp   As   System.Net.HttpWebResponse

                Dim   httpURL   As   New   System.Uri(url)

                httpReq   =   CType(Net.HttpWebRequest.Create(httpURL),   Net.HttpWebRequest)

                httpReq.Method   =   "GET "

                httpResp   =   CType(httpReq.GetResponse(),   Net.HttpWebResponse)

                httpReq.KeepAlive   =   False   '   获取或设置一个值，该值指示是否与Internet资源建立持久连接。  

                Dim   reader   As   IO.StreamReader   =   New   IO.StreamReader(httpResp.GetResponseStream,   System.Text.Encoding.GetEncoding( "GB2312 "))         '用GB2312字符

                Dim   respHTML   As   String   =   reader.ReadToEnd()   'respHTML就是网页源代码
                RichTextBox1.Text   =   respHTML

------解决方案--------------------
Try

HttpWebRequest httpWebResponse = (HttpWebRequest)WebRequest.Create( "http://www.baidu.com ");
HttpWebResponse response = (HttpWebResponse)httpWebResponse.GetResponse();
Stream stream = response.GetResponseStream();
StreamReader reader = new StreamReader(stream);
Console.Write(reader.ReadToEnd());
------解决方案--------------------
Function GetHttpPage(HttpUrl)
If IsNull(HttpUrl)=True or Len(HttpUrl) <18 or HttpUrl= "$False$ " Then
GetHttpPage= "$False$ "
Exit Function
End If
Dim Http
Set Http=server.createobject( "MSXML2.XMLHTTP ")
Http.open "GET ",HttpUrl,False
Http.Send()
If Http.Readystate <> 4 then
Set Http=Nothing
GetHttpPage= "$False$ "
Exit function
End if
GetHTTPPage=bytesToBSTR(Http.responseBody, "GB2312 ")
Set Http=Nothing
If Err.number <> 0 then
Err.Clear
End If
End Function