Looking at it again,
maybe the difference between the two adapters is:
- the "simple" one has a tab, this is used to focus.
- The complex one, there the lens itself is rotated and this will be transferred via the cam to the "body/adapter" helicoid.
And if they are the same with respect to lens heads, the first one fits "better" on the M-240 because live view can be used to do a little bit of semi-macro