Bootsector, mbr, /boot directory (partition), boot loader.
Code in MBR is typically called bootloader, but might be only one stage of the bootloader. From mbr, you might be sent to /boot directory (GRUB) or to the partition boot sector (Windows).
In Linux, /boot is where you also eventually load the kernel from
Suggestion to consider: Both OSes on the same physical drive (leave lots of empty space to use later for --eg backup
Format the other drive FAT32 and use it striclty for data---easy to access from either linux or that other OS