Apache::RegistryNG is the same as Apache::Registry, aside from using filenames instead of URIs for namespaces. This feature ensures that if the same CGI script is requested from different URIs (e.g. different hostnames) it'll be compiled and cached only once, thus saving memory.

Apache::RegistryNG uses an Object Oriented interface.
PerlModule Apache::RegistryNG
<Location /perl>
SetHandler perl-script
PerlHandler Apache::RegistryNG->handler
</Location>

Apache::RegistryNG inherits from Apache:erlRun, but the handler() is overridden. Aside from the handler(), the rest of Apache:erlRun contains all the functionality of Apache::Registry broken down into several subclass-able methods. These methods are used by Apache::RegistryNG to implement the exact same functionality of Apache::Registry, using the Apache:erlRun methods.

There is no compelling reason to use Apache::RegistryNG over Apache::Registry, unless you want to do add or change the functionality of the existing Registry.pm or if you want to use filenames instead of URIs for namespaces. For example, Apache::RegistryBB (Bare-Bones) is another subclass that skips the stat() call performed by Apache::Registry on each request.