I found it from http://www.php.net/manual/en/configure.about.php
These are the configure options of PHP compilation
--with-apache[=DIR]
Build a static Apache module. DIR is the top-level Apache build directory, defaults to /usr/local/apache.
--with-apxs2[=FILE]
Build shared Apache 2.0 module. FILE is the optional pathname to the Apache apxs tool; defaults to apxs.
What is meaning of static and shared?