List of Linux distributions

We are using Ubuntu as OS. Now in melborrn servers, we use CentOS.
Debian (Ubuntu) / Fedora (CentOS)
They belongs to different distributions.
Useful link:
http://en.wikipedia.org/wiki/List_of_Linux_distributions#RPM-based

To find, which linux distribution we use:
cat /etc/*release
or
cat /proc/version
or
uname -a
or
cat /etc/*version

http://www.linuxquestions.org/questions/linux-general-1/how-to-get-os-name-from-command-line-557339/

There are some differences in those distributions.
In Debian, we use app-get and In CentOS, we use yum.