PHPのDateTimeクラスが作り方によって色々違う

datetme.php

<?php

$date1 = new DateTime('@999994149');
$date2 = (new DateTime)->setTimestamp(999994149);

var_dump($date1->getTimestamp());
var_dump($date2->getTimestamp());

$diff = $date1->diff($date2);

print_r($diff);


print_r($date1);
print_r($date2);

var_dump($date1->getTimezone()->getName());
var_dump($date2->getTimezone()->getName());

result.md

タイムスタンプ同じで

int(999994149)
int(999994149)

時差はないけど

DateInterval Object
(
    [y] => 0
    [m] => 0
    [d] => 0
    [h] => 0
    [i] => 0
    [s] => 0
    [invert] => 0
    [days] => 0
)

オブジェクトの状態ちがうし

DateTime Object
(
    [date] => 2001-09-09 00:09:09
    [timezone_type] => 1
    [timezone] => +00:00
)
DateTime Object
(
    [date] => 2001-09-09 09:09:09
    [timezone_type] => 3
    [timezone] => Asia/Tokyo
)

タイムゾーンちがうし

string(6) "+00:00"
string(10) "Asia/Tokyo"