It's not the same linux across distributions

Many times I've read this in a lot of prime linux fora - It doesn't matter which distribution you're using as long as it's linux. Then the usual preaching of choice and freedom runs till the end of those particular threads. I don't buy to this generalized statement. Read on to know why, but first let's see how this statement surfaces from the so called evolved linux gurus.

An enthusiast Windows/Mac user jumps on linux enlightened by a friend or being encouraged on the web. He/she tries a so called popular distribution, if unlucky faces multiple problems related to the stuff on the outer layers, the gnu stuff and other OSS stuff which in combination with linux make a distribution. Then googles for a while, visits some fora, gets suggestions from seasoned and noob users to change his/her distribution with some other, where the issues in question are resolved but may face some other bugs. Then some guru drops in and says - linux is linux, doesn't matter which distro, it's best to use one that suits best for his/her particular needs.

Now on to the topic. In theory every distribution is the same, but in practice they are not. A developer or a long time user might feel it same after cleaning the clutter and sorting everything to his or her liking. But the average Joe is not that skilled and doesn't have that patience to tame the OS. A minor quirk that comes in the way might make him/her feel distro A is different from distro B which is quite different from distro C.

It's a pity reality. Linux distributions are so loosely integrated that a minor mistake in putting stuffs together will create major problems. Doesn't matter even if that distribution is byte by byte a recompiled copy or just a derivative of some popular distribution with minor changes here and there. Most often even if the derivative distribution shows superficial changes in skins, branding, selection of default apps or choice of desktop environment, it might influence components lying much deeper in the bundle. For example, take the case of audio stack (click on the image below) on a typical linux system. Look at its complexity and relationship with various components and imagine what can happen with slight mishandling.

Here's an interesting case of Scientific Linux 6.2 and Centos 6.2, both are free recompiled versions of RHEL, both aim to be as much close to the upstream as possible. I started with Scientific Linux, the installation was literally a non-starter on a Dell Optiplex 380. Checked mdsum, changed media from CD to USB to network. No go! However, CentOS had no such problem on the same PC.