we can get Date Difference using diff method of DateTime class.
I wrote common function for that. just you need to pass Date/DateTime String format or instance of DateTime class
<?php
    $currentDate = '2022-07-27';
    // $nextDate = '2022-07-27';
    // $nextDate = '2022-07-28';
    $nextDate = '2022-07-29';
    echo getDateToTodayTomorrowFormat($nextDate, $currentDate);
    /**
     * get Date format to number of Days difference Format ('Today', 'Tomorrow', '2 days later', '3 days later' etc.)
     *
     * @param  string|\DateTime $nextDate // eg. pass Object of DateTime class "OR" Date/Date-Time string (format :- 'Y-m-d', 'Y/m/d', 'Y-m-d H:i:s') 
     * @param  string|\DateTime $currentDate // eg. pass Object of DateTime class "OR"  Date/Date-Time string (format :- 'Y-m-d', 'Y/m/d', 'Y-m-d H:i:s') 
     * @return string
     * 
     * Date/Date-Time string must be in format of standard formats which are supported by \DateTime::class (https://www.php.net/manual/en/class.datetime.php)
     * 
     * ****
     * # Input > Output :- 
     *  $currentDate = '2022-07-27';
     * 
     *      case 1:- $nextDate = '2022-07-27',  `then OUTPUT :- "Today"` \
     *      case 2:- $nextDate = '2022-07-28',  `then OUTPUT :- "Tomorrow"` \
     *      case 3:- $nextDate = '2022-07-29',  `then OUTPUT :- "2 days later"`
     */
    function getDateToTodayTomorrowFormat($nextDate, $currentDate)
    {
        if (is_string($nextDate)) {
            $nextDate = new \DateTime($nextDate);
        }
        
        if (is_string($currentDate)) {
            $currentDate = new \DateTime($currentDate);
        }
        
        $interval = $currentDate->diff($nextDate);
       // $days = $interval->format('%r %d'); // returns like "- 1", "0", "+ 1"
        $days = $interval->days; // returns only 0 & int difference
        if($days === 0) {
            return 'Today';
        } else if($days === 1) {
            return 'Tomorrow';
        } else {
            return $days . ' days later';
        }
    }
?>
for more details see this stackoverflow question