Team 1 Script (private repository)
Linux Scoring Engine (Work in progress)
CIS Guide
You can think of Linux in two ways
Reading this article can help you understand what Linux is.
I recommend the article, but if you didn't read it, continue reading...
Kernel = a core program of an operating system
OS = kernel + ... (don't worry about this) + applications
Linux Distributions ("distros") = operating systems that have the (possibly modified) Linux kernel plus different software (differ mostly in desktop environment and package manager).
e.g., Ubuntu, Debian, Fedora, Arch, OpenSUSE, Tails…
there are distros for both desktop and servers computers.