Thank you for expanding on my question. You are preaching to the choir here to some extent since I have worked with low level details of OS in terms of Linux sy

Thank you for expanding on my question. You are preaching to the choir here to some extent since I have worked with low level details of OS in terms of Linux syscalls, drivers, scheduling, networking, filesystems (and crucially built 6502 based systems without an OS which was the real eye opener to see what you have to do to manage memory and hardware when one is not there) enough to give a much more thorough explanation of what an OS is if necessary. I have also never had an interviewer seem to want that level of detail. It probably depends on the job and the interviewer. I am a little skeptical that there is a large enough pool of people out there who can meaningfully compare Linux vs a closed source OS like Windows, other than maybe current or former Microsoft employees. But I agree with your overall point that comparative knowledge is good. I still struggle to find an accurate and complete single sentence definition, for if I were asked "what is an OS" in an interview though. Maybe I am being too pedantic and the best answer is just to start listing the parts or functions of an OS.