Basically means that the core OS files and systems can’t be changed. Everything else is stacked on top, and usually it means that you can rollback to a previous OS version if an update breaks something, without relying on any other image backup software.

Usually results a more stable reliable system, or at least one that’s easy to revert to working.

The downside being a reduction in flexibility and customizable options, and most programs need to be “containerized.”

I mean, it’s like 30 seconds to look up and change the default font in Word. It might even be part of the settings IT can change on a network level.