ABSPATH refers to the directory in which WP is installed. TEMPLATEPATH refers to the current theme directory, or the parent theme directory if you’re currently using a child theme. Both are WP constants, so are not available in PHP outside WP.
As for bloginfo('wpurl'), it’s not the same as either one of them; it echoes a URL rather than a file path. (And anyway, if that’s what you’re actually trying to do, you should be using site_url() instead.)
Thanks for the explanation between ABSPATH and TEMPLATEPATH, but now I have another question…
Let say the directory of my WP installation is:
http://www.hello.com/wordpress/
what differences will it makes if I use,
include_once(ABSPATH . ‘wp-content/themes/posttypes.php’);
and
include_once($url = site_url(‘/wp-content/themes/posttypes.php’, ‘https’); echo $url;);
The difference, as Amy pointed out, is that the first one is a file path, and the second one is a URL. The result is that the first option will work, and the second will most definitely fail.
