Reference: Http://stackoverflow.com/questions/10494574/what-is-the-difference-between-form-data-and-request-payload
If a request (typically POST) have Content-type header set to application/x-www-form-urlencoded the body was expected to be In the form of a, querystring with url-encoded Key=value pairs joined by &. Form Data section then shows the Key-value parameters (when viewed parsed). This-is-much more common in past because it's a default for HTML forms.
Other cases is shown in Request payload sections (and nowadays parsed for readability as well for common formats like JSON ).
If the requested Content-type is set to application/x-www-form-urlencoded, then this post request is considered an HTTP post form request and the parameters appear in the
In other cases, if a POST request that uses a native AJAX does not specify a request header, the default Content-type is Text/plain;charset=utf-8, and the parameter appears in the request payload block.
Ajax parameters appear in Request payload cause request.getparameter (name) to get a value that is not