What is the difference between array_merge and array_combine.

Array_merge - the elements of one or more than one array such that the value of one array appended at the end of first array. If the arrays have same strings  key  then the later value overrides the previous value for that key .

<?php
$array1 = array("course1" => "java","course2" => "sql");
$array2 = array(("course1" => "php","course3" => "html");
$result = array_merge($array1, $array2);
print_r($result);
?>
OUTPUT :
array
(
[course1] => php
[course2] => sql
[course3] => html
)

Array_combine - creates a new array by using the key of one array as keys and using the value of other array as values.
<?php
$array1    = array("course1","course2");
$array2    = array(("php","html");
$new_array = array_combine($array1, $array2);
print_r($new_array);
?>
OUTPUT :
array
(
[course1]  => php
[course2]    => html
)