There are two major trunks for most Linux distros. There are plenty of ground up distros, but most are derived either from RedHat using RPMs (RPM stands for RedHat Package Manager) or Debian using dpkg files. This file formats are used to install software on your computer. Currently, the biggest distros not derived from RedHat or Debian are Slackware and Gentoo which also have their own package management systems with various advantages/disadvantages.You can find the guide here
Some related Linux news from last week. Firstly we have Theo de Raadt from OpenBSD who claimed Linux is garbage. And then there was also an article which claimed Linux is it's own biggest enemy