Windows
Machine + peripheral management – The operating systems controls the whole machine and all the components in there. It also controls peripherals like keyboards, mouse, printers etc. For example Windows control monitor by changing the resolution, mouse by setting the click speed etc.
Security – Operating system needs to make sure that everything works properly and there is no unauthorised access that can harm your data. Windows has security functions like user accounts with password protection, crap firewall which is completely useless and other functions that can be easily bypassed by going to safe mode.
File management – Operating system needs to have file management to show files, create new files, deleting, editing and other functions linked to the files. Windows has his process called explorer.exe to handle the file management.
Device drivers – Drivers are programs that tell the operating system what and how to do with this particular device. For example when you buy new graphic card, to make it work properly with all of its power and efficiency you need to install drivers provided with the card.

MacOS
Machine + peripheral management – MacOS control of computer components are very similar, but almost all of devices need to be bought especially for Macs. For example MacOS can control keyboard by changing the input language. For other devices like iPhone MacOS controls screen by changing it to landscape mode.
Security – MacOS got security features like blocking the ports that are potential security issues. It also got security features that checks if the downloaded content is safe or not. In email programs attachments are not opened automatically so they can’t harm user computer without his knowledge.
File management – The program for file management that MacOS use is called Finder. It is pretty the same as Windows’ explorer, it got appropriate icon for every file type, the tree navigation system and trash on desktop.
Device drivers – Same as Windows’, the drivers are programs that controls the devices. In MacOS case, when the system is closed and you can’t really upgrade anything, every needed driver to run the computer is included in system. But when you want to install new printer, you got to install version of driver for MacOS.