array merge vs array join php code example

Example 1: php array_merge

<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
?>
Array
(
    [color] => green
    [0] => 2
    [1] => 4
    [2] => a
    [3] => b
    [shape] => trapezoid
    [4] => 4
)

Example 2: php merge 2 arrays

<?php
  $array1 = [
      "color" => "green"
  ];
  $array2 = [
      "color" => "red", 
      "color" => "blue"
  ];
  $result = array_merge($array1, $array2);
?>

// $result
[
    "color" => "green"
    "color" => "red", 
    "color" => "blue"
]