This sounds like a nefarious question but it's really not. I have a work laptop and I need to get some personal planning done after work tomorrow. Naturally I don't want to carry 2 laptops or run the laptop on the internal hard drive for personal use, but going back home and out again is very inconvenient. So my question is - would dual booting via an SSD (that I already use on another machine) leave any trace on the internal hard drive?
Honestly, I don't expect this to ever be a real issue, I doubt anyone will ever check or even care, but I just want to keep my work stuff entirely separate from my personal stuff. So if there's a fair chance I could muddy the two in any way by doing this, I won't - but it's my understanding that dual booting would be more or less adequately secure?
It wouldn't leave traces that would be likely to be detected unless you work in a national security sensitive area or other restrictive environment with very high security needs.
I admit I'm not familiar with the exact forensic traces in such a situation so this is largely an informed guess but assuming you're booting to Windows and the laptop has Windows installed already, your Windows install will touch the NTFS file system on that drive in a way that will leave forensic artifacts. Assuming you don't open it up and explore through the folders these would be extremely minor and unlikely to be noticed via automated means, only through an extremely thorough manual forensic examination.
Now UEFI may or may not give you trouble. You'd need to either disconnect the work drive or enter settings to change the boot drive to your new drive then change it back.
The thing to know about dual booting is assuming an operating system can read a drive (knows the file system, it's not encrypted) it can read the drive and everything on it. So if you have anything on your personal drive you don't want to chance your employer being able to see with work-spyware you wouldn't want to boot into your company install with your personal drive connected.
Other poster makes a point that Windows would not react well to being moved to another machine. It would probably trigger a demand to re-activate it which isn't a huge issue on windows 10. But the bigger problem might be drivers for hardware on your other machine being present and drivers for the laptop being absent.
All in all I wouldn't recommend moving disks with OS installs around and booting on dissimilar hardware if possible.
Windows 10, presumably 11 as well, doesn't seem to care about being moved to new hardware. Usually you just get the "please wait while we get ready" type of screen and it just works. Obviously game ready device drivers for graphics hardware could interfere, some laptops don't have great firmware for switching between a low power GPU and dedicated GPU without some specific drivers that Windows can't manage to automatically resolve.
Thanks for the in-depth explanation!