From Mexico.purplecow.org
While E2900 and E25K (also 6800/6900 etc) boards are very similar, they are *not* identical. The differences are primarily physical, due to the top-load design for the E2900.
First, the E2900 style system board, also known on the 1280/1290.
Next, the boards for the 25K and similar systems. Note the big handle on the right hand side.
Photographs of the hardware make the difference a lot easier to see. Note the handle/extractor mechanism on the E25K board compared to the flush-fit of the E2900 uniboard.