What’s the difference between implode() and explode()?

<?php
// implode(): ARRAY -> STRING
$names  = ["Rahul", "Manish", "Vikash", "Anshul"];
$joined = implode(",", $names);
echo $joined;               // Rahul,Manish,Vikash,Anshul

// explode(): STRING -> ARRAY
$fruits = "Banana,Apple,Mangoe,Kiwi";
$list   = explode(",", $fruits);

foreach ($list as $i => $fruit) {
    echo ($i + 1) . " - " . $fruit;
}