Two methods of PHP array fusion

$arr1 = array(
  10 => 'valueof10',
  11 => 'valueof11',
  'key1' => 'dataofkey1',
  'key2' => 'dataofkey2',
  'array' => array(
    'key1' => 1,
    'key2' => 'abc',
    'key3' => array(
      1, 2, 'name' => 'peter'
    ),
  ),
);

$arr2 = array(
  10 => 'newvalueof10',
  11 => 'newvalueof11',
  'key1' => 'newdataofkey1',
  'key3' => 'newdataofkey3',
  'array' => array(
    'key1' => 2,
    'key2' => 'defg',
    'key3' => array(
      1, 2, 'name' => 'jonathan', 'gender' => 'male'
    ),
  ),
);

array (size=6)
 10 => string 'valueof10' (length=9)
 11 => string 'valueof11' (length=9)
 'key1' => string 'dataofkey1' (length=10)
 'key2' => string 'dataofkey2' (length=10)
 'array' => 
  array (size=3)
   'key1' => int 1
   'key2' => string 'abc' (length=3)
   'key3' => 
    array (size=3)
     0 => int 1
     1 => int 2
     'name' => string 'peter' (length=5)
 'key3' => string 'newdataofkey3' (length=13)
 
array (size=8)
 0 => string 'valueof10' (length=9)
 1 => string 'valueof11' (length=9)
 'key1' => string 'newdataofkey1' (length=13)
 'key2' => string 'dataofkey2' (length=10)
 'array' => 
  array (size=3)
   'key1' => int 2
   'key2' => string 'defg' (length=4)
   'key3' => 
    array (size=4)
     0 => int 1
     1 => int 2
     'name' => string 'jonathan' (length=8)
     'gender' => string 'male' (length=4)
 2 => string 'newvalueof10' (length=12)
 3 => string 'newvalueof11' (length=12)
 'key3' => string 'newdataofkey3' (length=13)