The difference between Linux and Windows Operating system is the fact that Linux kernel and all of its components are free and open-source. Linux is what powers almost all supercomputers around the world. Android by google also runs linux kernel. There are alot of Linux Operating System out there, the list given here is good for Linux Enthusiasts coming from Windows Environment.
Most Linux distros are Debian based Linux Distributions and Red Hat based distributions. Examples of Red Hat based are CentOS, Fedora, Red Hat Enterprise Linux. Examples of Debian based are Kali Linux, Ubuntu, Kubuntu, Xubuntu, Linux Mint e.t.c.
Here is my top ten list of Linux Distros for Everybody 2014.
Ubuntu– Ubuntu is the most popular Linux distribution i know.It is powered by Unity desktop manager. Ubuntu descended from debian and most of its softwares are for debian as well.
Linux Mint – Linux Mint is an alternative to ubuntu with Cinnamon Desktop Manger. It is small in size and cool.It is based on debian and alot of softwares is available for it.
Fedora– Free Redhat make a distribution. You can run both KDE and GNOME desktop managers on it.Fedora uses Yum and RPM package managers.
PCLinuxOS- Lightweight,fast and stable is all i can say about PCLinuxOS.It features various desktop interfaces.
Arch Linux– Arch Linux is one of the most lightweight Linux Distributions with neat interface. It is easy to install and have bleeding-edge software selections.
Debian- Debian is the most popular, most stable Linux distribution of all times.
Kali Linux- This is Linux Distro for Security Professionals and Penetration Testers. It is debian based and is designed by Offensive Security. Kali Linux is Backtrack Successor.
ElementaryOS -Elementary OS have such an easy to use and sleek design that is eye-candy to the bottom.It is pretty much all anyone could want for their desktop.All the package managers for Ubuntu and Debian work here.It is also very stable.
CentOS– CentOS project recently released CentOS-7.0, super clean and hot. It is server based Linux distro. Get a copy for free and Enjoy.You can try CentOS minimal also.
SteamOS– SteamOS have improved graphics performance and Audion improvement as well. SteamOS combines the rock-solid architecture of Linux with a gaming experience built for the big screen.
After downloading your favorite Linux Distribution, install it and fire it up. You can use USB Drive to install it. If you install Debian based distro, we have a tutorial on Top Things to do after installing Ubuntu and what to do after installing Kali Linux for the very first time.