The samite board has bigger rails.
The DIN board has smaller rails.
Use the adaptor in the samite board, so you can clip 'smaller' timers that usually fit directly onto a DIN rail.
Slide the adaptor under the top lip of the samite rail, and clip it onto the bottom lip.
Attach your timer onto the adaptor.
Use the smaller filler to clip directly onto the board cover, to close the gap between the board and the timer.