TEMPLATEPATH
this is the physical path within the themes folder, to load a file called theme options.
if (file_exists(TEMPLATEPATH .'/theme-options.php')) include(TEMPLATEPATH .'/theme-options.php');
Where get_template_directory_uri()
can be used to register a custom stylesheet or load a header image at runtime, this is for the HTML rendering and will require the URL
wp_register_style( 'mycustomstyle', get_template_directory_uri() .'/styles/buckingham.css', '', '0.1' );
wp_enqueue_style( 'customstyle' );
This would load the stylesheet at runtime, here is an example where you can see the url for a custom stylesheet, you can see both examples here.
<link rel='stylesheet' id='customstyle-css' href='http://theme.digitalraindrops.net/wp-content/themes/raindrops-magazine/styles/buckingham.css?ver=0.1' type='text/css' media='all' />
For a child theme files that are not in the parent!
STYLESHEETPATH
and get_stylesheet_directory_uri()
HTH
David