Why doesn't a Thinkpad x260 motherboard fit into an x240?

The question is actually above. I want to replace the mb of my x240 with a newer one, because the x240 is slowly reaching its limits. As far as I know, replacing the old mb with an x250 with an i7 is no problem.

However, the internet says that the mb of an x260 would not fit into my Thinkpad and I wonder why. According to the description of the x260 board, the dimensions are identical and the screw holes are in the same places. Is there some other reason the board is incompatible? In itself it would be better to take the x260 board, as it is newer and the processor has a clear increase in performance.

Possibly other connections on the mainboard for screen, internal keyboard, etc.

The question is, what exactly is different, because for the keyboard, for example, there would definitely be a solution. With the screen, on the other hand, it could be problematic

Possibly do a little more research, otherwise just order the mainboard. You can always resell it if it doesn't fit.

In itself yes, just reselling it could mean a certain loss: / But yes, one possibility would be thank you