The 08BD020 is referred to as the core board.
The 08BD021X is referred to as the memory board.

These two boards are interchangeable. They appear different, for example, the 08BD020 has a 10 position dip switch, while the 08BD021X has an 8 position dip switch.

See the attached document showing the purposes of the dip switch and how to copy the memory from the old core board to the new memory board.

CSH
24 April 2014