Just to give you an idea - even on my laptop with over 10yr old technology, searching for updates on Linux takes 2s, then installation usually a few minutes max, completely done in the background, with no need to restart etc. And my guess is it probably works similarly on Macs.
Apple distributes OS-X (now MacOS) updates for apps dowloaded from their store (as well as OS updates/upgrades) through the App Store. Most app updates will install without a reboot, although they may require the specific app to be closed during the upgrade process. They bundle OS patches into batch updates, which *do* require a reboot to install and are quite large to download. A few of their built-in apps like iTunes and some raw camera file thingy come with independent updates, and I find those exceptions to be the most annoying.
I'm not going to comment on OS-X's ancient Commodore Amiga and early Mac-based multitasking model that was butchered on top of a Unix kernel, but will comment that my office at work is near a support center that sees their fare share of malware-infected Macs owned by people who drank the Apple Kool-Aid about not needing virus/malware protection.
In the name of disclosure, I must state that both my own home computer and my office desktop computer are Macs, and I work equally with Windows and Linux servers for a living. The only Windows computer in my house is my wife's notebook, because she refuses to use a Mac... and she complains all the time that it is acting strange. Everything else that I have a home runs on CentOS or Raspbian Linux. As I have said on multiple occasions, Windows 8 was the greatest sales tool...for Macintosh computers.....