Differences between files?
 

Sorry, I'm sure this is a pretty easy to answer question, I searched the forums on it, but couldn't find anything so what do I do with this file? I'm trying to update my autoconf, right now I have 2.57 and the newest version I found is 2.9-2. So what do I use to install this patch or w/e? thanks.

Depends on your distro. Usually the distro keeps tabs on the updates for tools, and it is just a matter of upgrading to the latest version using the package your distro has made available. If they haven't.. well there is always source you can compile :)