firespasm :
Thanks for your input, I will try and explore more than just Centos after I build up a base level of knowledge. I am actually looking at the Command Line Interface now, there's also a few webpages about which are helping me at the moment too
There are many different Linux distributions available, but many of this many different distributions are nothing more than slight modifications of other distributions.
RedHat Enterprise Linux (RHEL) is the gold standard for enterprise grade Linux distributions. It's a subscription based commercial product so it is not free to use. RHEL is the most widely supported distribution for engineering and design programs. It can certainly be used for home use and learning, but that would be a bit overkill. RHEL maintains a very conservative release cycle with major releases every 2 to 4 years and approximately 6 months between minor releases.
Community Enterprise Operating System (CentOS) is a binary clone of RHEL and many of the CentOS maintainers are RedHat employees. It maintains 100% binary compatibility with RHEL and contains all of the same free software as RHEL. It does provide access to RedHat's proprietary applications that are included in RHEL alongside the usual free software. CentOS is a good platform to learn on (in part because the detailed RedHat documentation is mostly applicable) but like its commercial brethren it does have a steep learning curve. CentOS releases track RHEL releases and are delayed by approximately one to three months. Version numbering is consistent between the two, so CentOS 6.5 has the same codebase as RHEL 6.5.
Fedora is a general purpose Linux distribution that serves as the upstream development branch for RHEL (that is, RHEL and by extension CentOS use a version of Fedora as a rough starting point). Fedora development is financed and directed by RedHat and serves as a testbed for new technologies that are too immature to be used in enterprise environments. It is also the operating system used by Linus Torvalds to develop the Linux kernel.
Fedora releases a new major version approximately every 6 months.
Debian is another enterprise grade Linux based operating system that serves as a popular upstream target for derivative distributions. Debian maintains a conservative major release cycle with approximately two years between major releases.
Ubuntu is a popular user-oriented Linux distribution that has historically derived much of its foundation from Debian. This has changed significantly in recent years. Ubuntu's aim is to create a home and user friendly environment, so it's often recommended for beginners. Ubuntu is also heavily used by hobbyists because it has a liberal release cycle of major revisions every 6 months and includes a broad collection of up to date software. The speed and scope of Ubuntu's revisions and lack of quality control have given it a less-than-stellar reputation in the enterprise sector though.
Mint is an popular desktop Linux distribution that is derived from Ubuntu and Debian. It is very media-centric and aims to "undo" some of the controversial elements of Ubuntu while continuing to focus on the user. Just as CentOS releases track RHEL releases, Mint releases track Ubuntu releases by approximately one month.
Most tasks are transferable between all operating systems that are based on a combination of Linux and GNU software.
Most remaining tasks are transportable between Fedora/RHEL/CentOS, and between Debian/Ubuntu/Mint
CentOS and Fedora are probably the best targets for "learning Linux". If you simply wish to use Linux, go with Ubuntu or Mint.