There’s a technical difference. On a single drive, GRUB (or any other modern bootloader) can handle multiple OSs that coexist on the same boot chain. Windows doesn’t like this of course. On different drives it is the UEFI that chooses which drive boot sector to boot from, regardless of which bootloader it has. Here, Windows doesn’t get a say, and it is less likely to break.
Historically, the first case was called dual booting but the second is not called that. If the same result is achieved, maybe the distinction doesn’t matter anymore. However, in the olden days, there was only one disk allowed to have a master boot partition, the Device 0 in an IDE bus. Consumer PCs were limited to two IDE busses, with a device 0 and device 1 each, only one hard drive could have an MBR on the primary IDE. Now a days it is much easier to have multi-disk boot capabilities in hardware thanks to EFI system partitions (since mid 2000s), but it used to be necessary to fiddle with an MBR even if the OSs were on different disks.
It is an important distinction because dual booting, as a concept, almost always exists in relation with Windows. If you have two, three or more Linux OSs running on the same disk drive, it is not called dual booting, it is just booting and choosing your distro, as bootloaders like GRUB are multi-booting by default.
So, yeah, maybe it is dual-booting as well, but it is not what the original term used to mean. It is just Windows wasting space in a quarantined disk, which I still prefer.
There’s a technical difference. On a single drive, GRUB (or any other modern bootloader) can handle multiple OSs that coexist on the same boot chain. Windows doesn’t like this of course. On different drives it is the UEFI that chooses which drive boot sector to boot from, regardless of which bootloader it has. Here, Windows doesn’t get a say, and it is less likely to break.
Historically, the first case was called dual booting but the second is not called that. If the same result is achieved, maybe the distinction doesn’t matter anymore. However, in the olden days, there was only one disk allowed to have a master boot partition, the Device 0 in an IDE bus. Consumer PCs were limited to two IDE busses, with a device 0 and device 1 each, only one hard drive could have an MBR on the primary IDE. Now a days it is much easier to have multi-disk boot capabilities in hardware thanks to EFI system partitions (since mid 2000s), but it used to be necessary to fiddle with an MBR even if the OSs were on different disks.
It is an important distinction because dual booting, as a concept, almost always exists in relation with Windows. If you have two, three or more Linux OSs running on the same disk drive, it is not called dual booting, it is just booting and choosing your distro, as bootloaders like GRUB are multi-booting by default.
So, yeah, maybe it is dual-booting as well, but it is not what the original term used to mean. It is just Windows wasting space in a quarantined disk, which I still prefer.