It's really not different number of drivelinks for the same size bar, the difference is in the length the bar is labeled with - it's not for real...
A 14" bar with the small mount (f.e. 250) is the same physical length as a 13" bar with the standard mount (f.e. 260), and a 16" bar with the small mount is the same physical length as a 15" standard mount bar. Hence, a 16" small mount bar is not the same length as a 16" standard mount bar, and that's why they have different drive link counts...
This is totally without any kind of logic, it's clearly just to confuse and embarrass people, there can't be another reason for this...
And as said, your 240 use the same bar mount as the 260.