calculate the difference between two times in PHP in both HH:MM:SS format and decimal format in PhP

<?php
    $start_time = "09:00 PM"; //    $start_time = "21:00:00";
    $end_time = "08:12 AM";   //    $end_time = "08:12:00";

    $time_format_A = DateTime::createFromFormat("h:i A", $start_time);
    $time_format_B = DateTime::createFromFormat("H:i:s", $start_time);
    if($time_format_A !== false){
        $start_datetime = DateTime::createFromFormat("h:i A", $start_time);
        $end_datetime   = DateTime::createFromFormat("h:i A", $end_time);
    }elseif($time_format_B !== false){
        $start_datetime = DateTime::createFromFormat("H:i:s", $start_time);
        $end_datetime   = DateTime::createFromFormat("H:i:s", $end_time);
    }else{
        return "";
    }

    // --------------------------------------------------------------
    // $start_time = "09:00 PM";
    // $end_time = "08:12 AM";

    // Create DateTime objects for start and end times
    // $start_datetime = DateTime::createFromFormat('h:i A', $start_time);
    // $end_datetime = DateTime::createFromFormat('h:i A', $end_time);
    // --------------------------------------------------------------
    // $start_time = "08:54:00";
    // $end_time = "12:21:00";

    // Convert times to DateTime objects
    // $start_datetime = DateTime::createFromFormat('H:i:s', $start_time);
    // $end_datetime = DateTime::createFromFormat('H:i:s', $end_time);
    // --------------------------------------------------------------

    // If end time is before start time, it means it's on the next day
    if($end_datetime < $start_datetime) {
        $end_datetime->modify('+1 day'); // Add 1 day to end time
    }

    // Calculate the difference as a DateInterval
    $interval = $start_datetime->diff($end_datetime);

    // Format the difference as HH:MM:SS
    $time_difference = $interval->format('%H:%I:%S');

    // Convert the difference to decimal hours
    $total_seconds = $interval->s + $interval->i * 60 + $interval->h * 3600;
    $decimal_hours = $total_seconds / 3600;

    echo "Difference (HH:MM:SS): " . $time_difference . "<br>";
    echo "Difference (Decimal hours): " . number_format($decimal_hours, 2);
?>