What's the difference between /etc/apache2/apache2.conf and /etc/apache2/httpd.conf?

Solution 1:

I believe you're refering to Ubuntu or Debian since they usually use this syntax of configuration files. If you look at the bottom part of apache2.conf you will see that it includes httpd.conf. You can read Ubuntu's explanation of what the files are meant to do at this URL:
https://help.ubuntu.com/11.10/serverguide/C/httpd.html