Difference of days, hours month , year on 2 dates

<?php

$today = date("Y-m-d H:i:s");
$datetime1 = date_create('2017-03-23');
$datetime2 = date_create($today);
$interval = date_diff($datetime1, $datetime2);


echo  " Current time ". $today."<br>";


echo $interval->format('%h hrs')."<br>";

echo $interval->format('%d  days')."<br>";

?>

Current time 2017-03-24 22:13:5922 hrs
1 days



$today = date_create(date("Y-m-d"));
$datetime1 = date_create('2018-12-23');
$datetime2 =date_create($today);
$date1=date_create("2018-12-15");
$diff=date_diff($date1,$today);
 $interval=$diff;


http://php.net/manual/en/dateinterval.format.php