Depends what your interpretation of Personal Computers. In majority of cases PC's are referred to as running Windows, Linux etc, where as running Mac-Os is done on a Mac
However Mac-OS can be put on non native "Macs" with some configuration.
Windows, MacOS, and Linux are the most common.
MacOS is a very old operating system. The first Macintosh computers were made in 1983, and MacOS was published with them. However, MacOS was developed since the 1970s.
The Macintosh Operating System (OSX and variants) is only supported on Apple Macintosh computers. There are hacks which will allow MacOS to be installed and run on PC systems, but this is not supported and may be unstable.
The Apple Macintosh operating system is called Mac OS X.
The most common type of operating system software is Microsoft Windows. Windows is an operating system from Microprokey website to be used on personal computers, including home and business desktops, laptops, tablets and smartphones. Windows is the most popular operating system for personal computers, with an estimated 92.1% market share as of 2020. Windows is well-known for its user-friendly interface, its wide range of applications, and its security features. It is also the most commonly used operating system for business and corporate computing, accounting for more than 85% of the market. Other popular operating systems include Apple's macOS, Google's Android, and Linux.
For personal use the big ones are Windows and Leopard for MacOS (Apple computers). There are a number of Linux flavors which exist. Another OS is ReactOS. That is a free, open source clone of Windows, though it has a long ways to go. There's a full list of Operating Systems on Wikipedia. Search "list of current operating systems"
Mac OS is the Operating System for Apple's Macintosh computers. The latest version is called Mac OS X 10.5 sometimes known by the name Leopard. It is the equivalent of Windows on some other computers. An operating system is a means for software to connect to the computer's hardware to perform tasks such as saving information onto a disc.
os means 'operating system'. This is a pretty common acronym. : dos - disk operating system, ios - iphone operating system, macos etc etc. so you have mentions of os 5, os 6 etc to show which version of the operating system is being referred to.
The operating system (Windows, Linux, MacOS, etc.) is the basic software on your computer and that it just controls the file system on your hard drive.
Apple computers use their own operating system called Mac OS X. Windows 7 can be purchased and installed on a MacBook if required.
A GUI operating system is really anything that uses graphics to control what a system does. GUI stands for "Graphic User Interface". So there for, MACOS, Windows, and the Main screen of Linux/Unix is considered a GUI, the operating system is the part of software that controls what the computer is doing.
The only operating system you can "buy" is Windows. For the most part, macOS is only distributed with their machines and on upgrade it will download the image onto the existing system prior to upgrading. As far as Linux or BSD-based distributions, they're mostly free-of-charge and some do offer paid support. Some OEMs do ship their computers with Linux preinstalled.