Lineage OS is an open source operating system for phones, tablets and computers based on Android - meaning it uses a modified version of the Linux kernel.

It works on 109 phone models giving a longer life to the phone, more security and more customization options than Android. It does have pre-installed apps but only essentials and is free from bloatware (unnecessary software often pre-installed by a phone's manufacturer or carrier).

Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds.
Linux is typically packaged in a Linux distribution.

From smartphones to cars, supercomputers and home appliances, home desktops to enterprise servers, the Linux operating system is everywhere. Linux has been around since the mid-1990s and has since reached a user-base that spans the globe. Linux is actually everywhere: It's in your phones, your thermostats, in your cars, refrigerators, Roku devices, and televisions.