为什么用 ajax 模拟 form 表单提交返回页面总是和直接 submit 提交的不一样

问题

RT 。网站是这个：
https://eq.wowow.co.jp/CGI/enq/engeki2015/index.cgi/conf/

网站传输用的是multipart/form-data,不过我用 post 模拟提交的数据和 submit 格式是一样的。
而且看了下两个的 request header 基本上也没差了，但是 respone 的 header 和页面就差了不少。后台没写过不清楚，看了下两个最大的区别应该是一个文档类型是document一个是xhr,想问下后台的话可以根据这个直接判定返回的页面吗？

相关数据：

我使用的代码：

var data={
    key:'conf',
    mem_flg:'',
    page:'1',
    back_page:'',
    '000021914':'ssd',
    '000021912':'男性',
    '000021913':'20 代',
    '000021911':'徳島県',
    '000021916':'sssd',
    '000021926':'dsds',
    '000021918':'dsdd',
    '000021920':'ads',
    '000021922':'adsds',
    '000021923':'',
    '000021924':'0001::同意する',
    '000021925':'0001::同意する',
    submit:'次　へ '
};
function sendData(data) {
  var XHR = new XMLHttpRequest();
  var FD  = new FormData();

  for(name in data) {
    FD.append(name, data[name]);
  }
  XHR.addEventListener('load', function(event) {
    console.log('Yeah! Data sent and response loaded.');
  });
  XHR.addEventListener('error', function(event) {
    console.log('Oups! Something goes wrong.');
  });
  XHR.open('POST', 'https://eq.wowow.co.jp/CGI/enq/engeki2015/index.cgi/conf/');
  XHR.setRequestHeader('Upgrade-Insecure-Requests', '1');
  XHR.setRequestHeader('Cache-Control','max-age=0');
  XHR.send(FD);
}
sendData(data)

submit 提交的 request header ：

POST /CGI/enq/engeki2015/index.cgi/conf/ HTTP/1.1
Host: eq.wowow.co.jp
Connection: keep-alive
Content-Length: 1778
Cache-Control: max-age=0
Origin: https://eq.wowow.co.jp
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.80 Safari/537.36
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary5LSRJwQdceXFo8uo
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
X-FirePHP-Version: 0.0.6
Referer: https://eq.wowow.co.jp/CGI/enq/engeki2015/index.cgi/conf/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: wowow2_MGSID_AuthTicket=57d35173edd644dac7cca0ada9fe586a2b874b7a; wowow2_MGSID=0117130a152e480144668844800011862; enq_plus_000002528=6645110a152e550144677804300003180

submit 提交后返回的 respone header ：

HTTP/1.1 200 OK
Date: Fri, 06 Nov 2015 02:48:44 GMT
Server: Apache
Pragma: no-cache
Cache-Control: no-store, no-cache, post-check=0, pre-check=0
Expires: -1
Keep-Alive: timeout=2, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html;charset=UTF-8

ajax post 模拟的 request header ：

POST /CGI/enq/engeki2015/index.cgi/conf/ HTTP/1.1
Host: eq.wowow.co.jp
Connection: keep-alive
Content-Length: 1754
Origin: https://eq.wowow.co.jp
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.80 Safari/537.36
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryj73JdouNDpXuT6ep
Cache-Control: max-age=0
X-FirePHP-Version: 0.0.6
Accept: */*
Referer: https://eq.wowow.co.jp/CGI/enq/engeki2015/index.cgi/conf/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: wowow2_MGSID_AuthTicket=57d35173edd644dac7cca0ada9fe586a2b874b7a; wowow2_MGSID=0117130a152e480144668844800011862; enq_plus_000002528=6645110a152e550144677804300003180

ajax 提交后返回的 respone header ：

HTTP/1.1 200 OK
Date: Fri, 06 Nov 2015 02:49:37 GMT
Server: Apache
Keep-Alive: timeout=2, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html;charset=UTF-8