I think the word is "freedom". What difference does it make what these people do? Linux isn't some monolithic corporation intent on making money and there is more emphasis on freedom than conformity. People do this because they want to and they can. Like the reference above to cars, people customize and modify vehicles to their own taste all the time, because they want to and they can.

You're confusing me now! First you say that Linux is basically the same under the hood (so to speak) and now you want everything the same and say they aren't and it's disorder. It's just freedom. There are international standards for various things in IT and Linux pretty much complies with them AFAIK. So far there isn't total monolithic, monopolistic totalitarian control of everything.

So basically, Linux is free and we all have the freedom to use it as we see fit. I don't see why you or anyone would be concerned with this.

Yancek,

It just seems little scary to me (and for many beginners, I'm sure). Listen, how in a world once can handle/troubleshoot 20 different editions, each with its own scripting policies, different locations of configuration files, administrative practices etc. Like you come to a job interview, they're asking you "do you know linux?"
So if I learn it with Centos (about which I have few questions too), would I be qualified to say "yes", or there's a portfolio of linuxes that I have to be familiar with to asnwer "yes".

If your truly know a linux then you will know some programming languages, protocols, and utilities to work with these things. Programming languages and protocols are used in all computing, not just linux. Anyone can remember commands, and you can teach anyone to add a user to a system via command line. Actually knowing what is going on in the background can be easily translated from one flavor of linux to another (for the most part). So my feeling is if you know one linux you know them all, you might just have to learn a new syntax.

They arent that different. Sure, there are differences, and I'm not saying that someone who is really experienced with distro XYZ will be able to move to distro ABC and be as competent. But once you have the general idea, moving from one distro to another isnt that hard.

IMO beginners are better off getting the hang of whatever distro they choose, not trying to be a master of all distros. That would be like trying to learn how to cook every national cuisine style when starting to learn cooking.

I've never been asked "do you know linux" in a job interview. I have been asked "do you know distro XYZ", which is much easier. "Do you know linux" would be a pretty silly question if you were after experience in a particular distro, like asking "do you know windows" without making it clear if you are talking about Win9X, WinNTto 4.X, Win2K/XP, Win Vista/7, and all the 'server 20XX' versions.

I'll point you back to what snowpine posted as well-

That is pretty generalised,but true.

So if you get asked "do you know ubuntu" (which I have been asked at a job interview), and you dont have any ubuntu experience but you do know debian, its easy to say "I dont use ubuntu, but I know debian, I should should get the hang of it pretty quicky".

The same would be true for .rpm distros, though there is probably more of a spread of distros using .rpm than there is .deb distros. Source based, there is far more differences, but if you have got your head around a source-based distro, then moving to a .rpm or .deb distro should be pretty easy.

If you are applying for a job and the interviewer asks if you know Linux I would assume they use Linux. If they do, they should have some familiarity with it and know that there are hundreds of different version - mostly because it is open source so anyone can modify and create whatever they want. If you are going to be working with servers, there are just a few versions which are popular and widely used. If you are going to be working with home user computers, again there are just a few (more than servers though) which are popular. There is no reason why anyone would need to be familiar with all versions.

You'd probably be best off using a popular version to learn basic commands and one of the more popular distros for server, which are probably CentOS (Red Hat), Suse, Debian and ??? don't have any actual statistics?

As a newbie there are only 3 things you need to worry about.

1. The desktop, KDE, Gnome, others This is just a personal choice.
2. Package manager, Synaptics, apt-get, yast, etc. Again forget the technical reasons, which one do you like to use.
3. The community. How friendly they are, how easy it is to understand their answers. Lurk in them and look for common problems like wireless and video and read the responses.

After you get the hang of those then you can deal with the more technical areas.

I cannot disagree and in fact have learned from what others have posted.

I'll add this:

In addition to package handling, the other major difference I've noticed is in startup scripts and the structure of /etc (the directory that holds system configuration directives).

Debian and Fedora and their derivatives use variations on the Unix System V startup scripts.

Slackware and Slackware-based distros use BSD style scripts. (Frankly, I find the Slackware way much more straightforward).

I'm rather new to linux, and didn't know to much when I was choosing my distro. But I looked around (it's how I found this forum) read stuff on google, and ran into the same thing your talking about. I couldn't really notice a difference. So I asked my self what I wanted my computer to have. My list was: Space (Some distros are as small as 50MB) next was speed (I didn't want it to be packed with programs that would be memory hogs, and leave to much behind even if I shut them down), I wanted simplicity, so something with admin tools was for me, because I didn't want to have to do 90% of the work ... After I got dreamlinux, My cousin got ubuntu on his system, and didn't do a partition and is only using one account (Root - Don't worry I told him not to :P ) ... it ran a bit lagg-ier then mine and his PC his better ... So if you use someone else's linux machine with them having different settings, you may see a difference. And as said before, the file format is different .deb is what mine uses, others use other format. If you want to be technical all OS are the same, Windows has a bootscreen, a login, a shell, a control panel, and a task bar. So does linux. so does the PS3. Linux is different (even from itself) by means of Control over the system, Accessibility, User friendliness, and focus (by which I mean if you are using your computer for sound recording, There are media distros with nothing but media apps, if you are a novelist, get a distro with only openoffice,textpad, and internet.) which can save disk space, leaving you a bit of freedom. I don't know if this is how you were looking to have your question answered, and I don't know much about linux other then what I outlined here lol ... I hope you at least found some of this useful. Good luck in your search to discover the differences!

So, what would be your recommendation on a distro. Which one should I go with? I hope, on some point, using Linux skills for employment. I can't really go wide. I have to concentrate on something that gives me better chances. From what I read it appear like Red Hat is undisputable Number 1, and openSUSE is remote second? Am I right? Guys I'm asking only about popularity of distro, not which one is the best!

Red Hat is and has been number one for Linux servers for quite some time and Suse Linux or Opensuse would be second. CentOS is the free version of Red Hat so if you're going to be looking for that type of employment, I would say that would be your best choice. Distrowatch has a lisiting of most popular desktop distribution which is always current. Don't know where to get info on Linux servers although I've seen in it the past.

Since you can download and try both CentOS, Opensuse for free (as well as others)you might do that and take a look for yourself.

So CentOS it be! But why there's CentOS which is apparently the same as Red Hat but named differently? I mean is it the SAME thing but just named differently? Why to have two names of the same thing?! Sound like religious superstition!

It most likely comes packed differently, Like I have Dreamlinux ... It is the same thing as Debian, runs the same, looks the same, uses same commands ... Only difference is that I have more media options (CD player, DVD, Burning devices, etc) ... I'm willing to bet that CentOS just has other tools you can utilize. You may want to look at what the distros your looking to get come with as far as things you will need to help you along.

Redhat
CentOS

and HERE is a site that details using CentOS as a server, starting with download to istallation, to using as a server. It is 7 pages worth of reading, but should be able to help you along, IF you decide Cent is what you want.

Has nothing to do with religion. CentOS is simply the free version of Red Hat. If you want to use Red Hat you have to pay for it, but you will get support and can use the RHN for updates and installing software.
CentOS is basically the same, but without the Red Hat-branding, so that you can get it for free. But you won't have commercial support.

From the few distros you posted:

Ubuntu is based on the current Debian distro, rather than a true fork of Debian. Both use the Deb package system. Starting and controlling processes are influenced by BSD Unix.
Ubuntu uses the Gnome desktop. For each desktop, there is a different Ubuntu variant. This is due to the program where Canonical send a free CD to people requesting one. Installing from one or two CDs limits the desktop and program selection.

CentOS is a based on Red Hat. The free variant of Red Hat is Fedora. These three will be very close.
SuSE, Mandriva and Fedora Core all use the RPM package system. Mandriva (formally Mandrake) is a fork of an early Red Hat distro. SuSE and Red Hat were forked from Slackware. Red Hat developed the RPM package system, and SuSE adopted it.
These distros support several desktops. They all use the System V Unix method for starting and controlling background processes.

Nice explaination..