|The Offical Microsoft defination of boot drive is where the OS resides. System disk is defined as where the boot files are located.|
There is some confusion in the industry because for years Microsoft called where the boot files were located the boot drive. For example in MSDOS days io.sys, msdos.sys and command.com were located at the root of c: and that was the boot drive.
Now the boot drive is where the OS resides so for example where the Winnt or Windows folder resides. System is where the boot.ini, ntldr and ntdetect reside.
Note that with everything on one partition it is both boot and system.
Here is a link you may find interesting.
Here is the offical MS view which you will find matches what I have written
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