The main difference between isset() and array_key_exists() function is that the array_key_exists() function will definitely tells if a key exists in an array.

1. Code:

<?php 
  
$array = array(
     'name' => null,
);
 echo"Result for array_key_exists():"."<br>";
echo array_key_exists('name', $array) 
? 'array key exists' : 'array key does not exist';
echo"<br>"."Result for isset():"."<br>";
echo isset($array['name']) ? 'array is set.' : 
    'array is not set.';
?>

2. Example:

Input:

$array = array(
     'name' => null,
);

Output:

Result for array_key_exists():
array key exists
Result for isset():
array is not set.

3. Difference between isset() and array_key_exists():

The main difference between isset() and array_key_exists() function is that the array_key_exists() function will definitely tells if a key exists in an array, whereas isset() will only return true if the key/variable exists and is not null. Also isset() doesn’t render error when array/variable does not exist, while array_key_exists does.