这些参数的含义相同，只是命名不一致。两者都接受对函数的调用。这甚至可以是相同的功能。

这里是一个简单的插件演示。Download

/*
Plugin Name: Callback Demo
Description: Demonstrating how a meta box and a menu page can take the same callback function.
Version:     1.0
Required:    3.1
Author:      Thomas Scholz
Author URI:  http://toscho.de
License:     GPL
Plugin URI:  http://wordpress.stackexchange.com/q/24481/
*/
! defined( \'ABSPATH\' ) and exit;

add_action( \'admin_menu\', \'wpse_24481_demo\' );

/**
* Adds a menu page and a meta box with the same callback function.
*
* @return void
*/
function wpse_24481_demo()
{
    $title    = \'Callback Demo\';
    $callback = \'wpse_24481_callback\';

    add_menu_page( $title, $title, \'edit_posts\', \'callback-demo\', $callback );
    add_meta_box( \'callback-demo\', $title, $callback, \'post\' );
}

/**
* Prints the content.
*
* @return void
*/
function wpse_24481_callback()
{
    print \'Here may be dragons.\';
}

结果

“页面”菜单

<小时>

meta框