There is a very strong correlation between the wealth of the kids on my module, and the device they have.
Mac users really struggle to understand the concept of local files without being shown. PC users, alas, snort too much SharePoint these days to be considered healthy - trying to save a word document locally these days is like climbing a mountain blindfolded. As for the Chromebook kids, they do their best with what they have, and given how little compatibility those devices have with the software I teach, I'm proud of them.
Most of the time it's realising the difference between local and cloud storage. A lot of students get confused when trying to upload their first coursework - usually it's solved by just showing them the difference between local files (this is stored in a permanent local place) and cloud storage (this is stored permanently somewhere else).
Mac users really struggle to understand the concept of
For me, it was trying to explain to a Mac user that she should have a separate profile on her Mac for work vs. personal
She'd convinced her employer that she could work from home using her own Mac (the office was all Macs except for the video production suite), and he said OK. Didn't ask me, of course. Despite me saying a long time ago when someone else floated the idea, that it was poor practice from a security viewpoint.
Then three days later the call came - "I can't access work files". So I remote in, she's got links to her personal iCloud Drive directories somehow mixed up with the work Google Drive.
I started to explain about using a different profile for work and just got a blank stare.
"You log off your personal profile and log into the work profile"