Conditional tags are used to change content on the basis of what conditions a page meets. While there are no conditional tags depending on a user’s role, this is how you can manipulate content depending on roles:
Display content to the user, depending on his role
<?php
global $current_user;
get_currentuserinfo(); //not strictly required, $current_user should be populated anyway
if(in_array('editor', $current_user->roles)) {
// echo markup here
}
?>
Alternatively, you might also want to check out current_user_can()
Edit: Display content based on a commentator’s role
<?php
$commentator_id = get_comment(get_comment_ID())->user_id;
$commentator_info = get_userdata($commentator_id);
$capabilities = $user_info->wp_capabilities;
if (array_key_exists('editor', $capabilities)) {
// echo markup here
}
?>
The above will have to go in the comments loop.
Resources:
get_comment() | get_user_data() | Comment Loop Beauty