Admin and User Scripts

[Anon]

I want to make a script taht both admins ans users use. As the admins are authenitcated differently, I want them to see a different page (with editing options)
Would I do it like this?
(pseudo code)
if//authenticate admin using function {
?>
HTML here
<?php
exit();
} else {
?>
USER HTML here
<php
exit();
}
?>

[Anon]

<?
if ($user == admin) {
// display admin stuff
?>

you are admin.

<?
}
else {
// display user stuff
?>

you are user

<?
}
?>

no need to use exit function.