Every Linux operating system uses the same kernel, so it's natural for them to look somewhat similar. Of course, there are also features (applications) that set them apart. For example, package managers differ between the major distributions, as does the way each distribution installs.
It should be mentioned that although most Linux distributions today are easy to install, there are some who have difficulty, perhaps because they are waiting to turn on their computer and get it working…
Below we will see some distributions that are very difficult to install. The following distributions are not for everyone, or rather to put it better: if you don't have the time to spare, better not bother. 
What makes an installation difficult?
Generally speaking, the fewer options a distribution has, the harder it is to install. Below we will see a list, in which we will not mention Debian or Arch. Yes, I have heard that Debian is difficult to install because the drivers are not installed automatically…
Why would someone install one of the following distributions?
Personally, for me it was the challenge, the curiosity and the research and of course the search for new knowledge.
Slackware
The oldest Linux operating system, Slackware, is a bit difficult to install, although it provides very good documentation on the installation disc, installs a root system on its own, and doesn't even require an internet connection.
Like Debian (and unlike simpler Linux operating systems like Mint), during the installation process, you are given the option to select groups of software packages that you want to have by default, but also to exclude other packages that you don't need.
The result is that you may need to know what each package does and why it is needed.
Another feature that makes Slackware a bit more difficult is that you will have to create space on your disk manually using the command line tool fdisk or cfdisk.
However, you are given many basic command line tools to configure Slackware, since it doesn't use a GUI like Debian.
Did you have any difficulty? Compared to the following Linux operating systems, installing Slackware is a breeze
NuTyX
The NuTyX Linux operating system is aimed at users who want flexibility and power. That alone should ring a bell if you're interested in easier distributions.
Unlike Arch, which from a certain point in the installation onwards has a rudimentary graphical interface, you will have to install it with a command line tool, first to partition your hard drive, and then to proceed with the installation.
By the end of the NuTyX installation process, you will have a very basic system to build from scratch. Unlike Slackware, however, you will need to install all the other programs you need from the command line.
Gentoo
Of course, the Linux distribution known for its difficult installation could not be missing from the list.
Like NuTyX, you will need to know a lot about your system and Linux in general, along with the right tools to use for configuration. In short, there is no installer and everything is done from the command line or terminal.
With Gentoo Linux, the choice is yours. You get to build exactly the system you want, without actually building it from scratch. That's one of the reasons Google's Chrome OS is based on Gentoo.
It should be mentioned that Gentoo's documentation is excellent, for whenever you encounter a problem. The wikis provided by the distribution are very detailed, and the sheer amount of information they contain makes them difficult to read.
This is because the distribution does not have many features that are given in other Linux operating systems. Many pages are needed on the wiki for manual options in Gentoo. For example, you can build your own kernel….
Linux From Scratch (LFS)
Linux From Scratch (LFS) is not an operating system in itself. It provides its users with a way to build their own operating system. We can call it more of a “blueprint” that is used to build the foundation.
So the Linux From Scratch (LFS) blueprint gives the reader every step of the way to make their own operating system.
The end result is the same (?)
At least in appearance. Do you prefer security, or watching movies and writing on Facebook? If you want the latter, you've read all of the above for nothing... you're in the wrong publication.
It's important to mention that no matter which Linux operating system you choose to install, what matters is finding the one that works for you. Sure, there are pros and cons to comparing distros, but we're always talking about Linux.
Choose what suits you best. Do you want to learn and experiment or do you want something more automated?
Anyway, it's all Linux.
