Hour difference between two times(HH:MM:SS a)in momentjs

try below code

// start time and end time
var startTime = moment("12:16:59 am", "HH:mm:ss a");
var endTime = moment("06:12:07 pm", "HH:mm:ss a");

// calculate total duration
var duration = moment.duration(endTime.diff(startTime));

// duration in hours
var hours = parseInt(duration.asHours());

// duration in minutes
var minutes = parseInt(duration.asMinutes())%60;

alert (hours + ' hour and '+ minutes+' minutes.');

check fiddle here http://jsfiddle.net/nil4you/gs69Lv5x/

Get Hours

I got the hours by using this code

endTime.diff(startTime, 'hours')

Get Minutes

i got the minutes by using this below code

var mins = moment.utc(moment(endTime, "HH:mm:ss").diff(moment(startTime, "HH:mm:ss"))).format("mm")

My Working code is

$scope.UpdateTimeSheet = function (rowEntity) {   


            if (rowEntity.StartTime.toString().length != 11) {
                rowEntity.StartTime = moment(rowEntity.StartTime).format("hh:mm:ss a");
            }
            if (rowEntity.EndTime.toString().length != 11) {
                rowEntity.EndTime = moment(rowEntity.EndTime).format("hh:mm:ss a");
            }

            var startTime = moment(rowEntity.StartTime, "hh:mm:ss a");
            var endTime = moment(rowEntity.EndTime, "hh:mm:ss a");

            var mins = moment.utc(moment(endTime, "HH:mm:ss").diff(moment(startTime, "HH:mm:ss"))).format("mm")

            rowEntity.TotalHours = endTime.diff(startTime, 'hours') + " Hrs and " + mins + " Mns";

}

var startTime = moment("12:16:59 am", 'hh:mm:ss a');
var endTime = moment("06:12:07 pm", 'hh:mm:ss a');

endTime.diff(startTime, 'hours');