The meta tags have nothing to do with what is displayed on the page, they are all in the head section of the site page.
header.php effects what is displayed on the page.
I think (personally) sales message and tagline are being used interchanably.
My assumption is that when people ask this question they are refering to what is displayed on the page and not what is hidden in the head section.
This is from meta_tags.php
* @version $Id: meta_tags.php 2555 2005-12-13 05:37:01Z drbyte $
*/
// page title
define('TITLE', 'make changes here');
// Site Tagline
define('SITE_TAGLINE', 'make changes here');
This is from header.php
* @version $Id: header.php 2848 2006-01-14 09:47:08Z wilt $
*/
// added defines for header alt and text
define('HEADER_ALT_TEXT', 'make changes here');
define('HEADER_SALES_TEXT', '<h1>make changes here</h1>');