PHP 合并数组运算符 + 与 array_merge 函数

<?php
$cfg = [
    0 => 'cfg-1',
    1 => 'cfg-1',
    'name' => 'hlq',
    'age' => 18,
    'job' => 'engineer'
];

$default = [
    0 => 'default-0',
    1 => 'default-1',
    'name' => 'hlq',
    'age' => 16,
    'hobby' => 'readding'
];

var_dump($cfg + $default);

var_dump(array_merge($cfg, $default));