Not particularly expensive, for Windows, is a program called Allway Sync. The free version allows trial configurations, but when usage reaches an undetermined point, money is required.
It allows for local to local drive synchronization, local to external sync, folder to folder sync, just about anything you can imagine.
The profiles can be individually to ...
For anyone looking for the same kind of software - ended up using Allway Sync.
Works for syncing both from and to external drive.
Detects differences and added/updated/deleted files.
free version is enough for my needs
Wouldn't call it very user-friendly or one-time-settupable
All in all it works and does exactly ...
You could use robocopy from the command prompt. You could also put it in a batch file if the source and destination disks do not change their drive letters over time.
And since you’re using Windows 10, robocopy is already installed with it. (It can be downloaded for some older versions of Windows, but you shouldn’t need to do that with Windows 10).
You could use robocopy. It's already on board, is very customizable (w.r.t. to ecxlusion criteria etc). And does a pretty awesome job.
However, otoh you would still be well advised to consider investing a minimal amount of time in really putting your jupyter file in a subfolder. Just makes life far easier. I'd think, moving the files in the subfolder now ...