代码一： 

$.ajax({
                url: "AjaxPassenger.aspx",
                cache: false,
                data: "Date=" new Date() "&cPassengerName=" encodeURI(ctxtName) "&CerType=" cddlCerType "&CerNo=" ctxtCerNo "&Phone=" ctxtPhone "&validateKey=validateKey&Num=1",
                async: false,
                success: function(count) {
                $("#cspanPageTotalCount").text(count);
                }
            });

代码二：
            $.getJSON("AjaxPassenger.aspx",
            { Date: new Date(), cPassengerName: ctxtName, CerType: cddlCerType, CerNo: ctxtCerNo, Phone: ctxtPhone, PageIndex: PageIndex, validateKey: "validateKey" },
             function(json) {
                 var html = "<tr><th>中文名称</th><th>证件类型</th><th>证件号</th><th>电话</th> <th>操作</th></tr>";
                 if (json.length > 0) {
                     for (var i = 0; i < json.length; i ) {
                         html = "<tr align=\"center\"><td>" json[i].ChineseName "</td><td>" CertypeList(json[i].CerType) "</td><td>" json[i].CertificateNo "</td><td>" json[i].Phone "</td><td><span onclick=\"btnxianzhe(this)\">选择</span></tr></td>";
                     }
                 } else {
                     html = "<tr><td colspan=\"5\">您当前还没有常旅客</td></tr>";
                 }
                 $("#tabPassenger").html(html);
             });

请问这两段代码有啥区别？给我感觉都是异步调用得到返回值，为什么一个用 $.ajax一个用$.getJSON，难道是一个是接收集合，一个是单个对象么？