An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. (source: Wiki).
All major platforms (hardware and software) require an operating system. In general, OS is a software that allows users to run other application programmes in a computing device. Ubuntu and Mac are the second most common desktop OS after windows.

History Of Ubuntu

Linux has come with a lot of distros and its popular distribution is Ubuntu. Linux was already established in 2004, but it was not open source for every user. Hence Mark Shuttleworth decided to make a team of developers from the one of established project Debian and create an easy to use Linux desktop: Ubuntu. Ubuntu has free software available for all and funded through a portfolio of services provided by canonical.

Linux is a popular open-source operating system which is also referred to as Linux kernel. Linux is an open-source platform where user can download it and modify its source code. It is the most-used OS for desktop and server application. It provides all necessary components (tools, service and programmes) for a fully operating system.

They give special privilege to some highly qualified developers for being part of their free software foundation as Linux/GNU to build a better community. Many companies in the market make various Linux OS and core kernel with all components but Linux kernel is developed and maintained by Linux foundation.

Releases:

Ubuntu released on 20 October 2004 and it’s latest released version is Ubuntu 19.4 (18 April 2019).

Linux kernel was first released on September 17, 1991, by Linus Torvalds. It was originally developed for Intel x86 computers but later, ported to other platforms as well. Having dominancy in android OS smartphone, Linux has highly installed in the general-purpose operating system.

Linux is the foundation of many opearting systems like Android, Arch Linux, Debian Linux, Gentoo Linux, Ubuntu, Mandriva Linux, Pc, red hut Linux, Sabayon Linux, Slackware, Suse Linux.

History Of Mac OS

Mac OS is an operating system of Apple computer Mactonish series, (computers and workstations) having a graphical user interface which is only developed and maintained by Apple engineers themselves. Apple developed the whole system including Kernal, desktop environment and pre-installed software. Mac OS is the second major series of Mantonish operating system.
Apart from all specifications, it looks better than other systems as well.(personal preference)

For Complete detail about this:- https://codersera.com/blog/ubuntu-vs-mac-os/