Merely Linux
There are many distributions of Linux. While the differences between them are important to some, many differences are not that important for others. All of the parts of linux can be switched. A distributions is just a collection of parts. Linux is open source, peer reviews, and people are working to make it better while at the same time new technologies are emerging.
In fact if you are so inclined you could make your own distro ... see linux from scratch ...
You can also create your distribution by changing an existing distribution and building an your own ISO. Most distributions are based off of debian. The program genisoimage can be installed via the package manager to build the ISO of your current linux. It is commonly used to make a backup of your existing system.
$ genisoimage -o [file-name.iso] [ directory-path]
Are Android and Chromebook Linux devices? distros?
If Linux were a commercial product like Windows, they would certainly be Windows devices. But one may also consider them as applications that run on Linux, which can run applications within themselves.
Being a Linux distribution however may infer to many that the GUI can be swapped out, but with Android and Chromebook if the GUI is swapped out are they still Andriods and Chromebooks?
Andriod does not have a built in command prompt, but one can be installed through the game store and one can "apt install python". ChromeBook has a terminal with a distribution of linux that runs in a virtual machine under ChromeOS. Both Andriod and Chromebook are running the Linux kernal.
Enterprise Level Security
Linux is built on Unix best practices to keep the system secure. This means programs and data are kept in different folders. The program folder can only be written to by someone who has an appropriate level to change and modify the program data. See Linux folder structure.