What is difference between strstr() and stristr() ?

In PHP both functions are used to find the first occurrence of a substring in a string except
stristr() is case-insensitive and strstr is case-sensitive, if no match is found then FALSE will be returned.

Sample Usage:

<?php 
$email = ‘abc@xyz.com’;
$hostname = strstr($email, ‘@’);
echo $hostname;
output: @xyz.com
?>

stristr() does the same thing in Case-insensitive manner.