Windows classifies USB drives in two groups: USB disks and USB sticks.
This classification is controlled by the value of the
"removable media bit" in the controller of the USB drive.
For USB disks the "removable media bit" in the controller of the USB drive contains the value 0.
Windows treats such drives like fixed disks. Especially it is possible to create
multiple MBR partitions on USB disks and Windows will show all partitions supposed their file system is recognized by Windows.
However in most cases the "removable media bit" in the controller of the USB drive contains the value 1.
Windows considers such drives as USB removable drives, in short USB sticks.
Windows can access on USB sticks only the first MBR partition. It is possible to create additional
MBR partitions on an USB stick. However, these additional partitions are ignored by Windows, they never show up in the Windows explorer.
Set partition accessible:
Starting with Boot-US 3.5.0 you can select which partition on the USB stick should be accessible by Windows.
The selected partition is moved by Boot-US to the first position in the partition table. This partition remains accessible by Windows
until you set another partition on the USB stick as accessible.
In Boot-US the accessible partition is marked with the partition number 1.
This new function requires a 3.x.x license if the USB stick contains more than two partitions.
Linux does not distinguish between USB disks and USB sticks. All partitions on USB disks and USB sticks are accessible.