you can create new Date from your time strings and compare
var start = new Date("November 1, 2014 " + $("#timepicker").val());
start = start.getTime();
var end = new Date("November 1, 2014 " + $("#timepickerTo").val());
end = end.getTime();
if(end >= start)
{
alert("OK");
}
DEMO[
^]