I've noticed on many used MacPro listings that people have upgraded a MacPro4,1 (a.k.a. 2009) to a MacPro5,1 (a.k.a. 2010) simply by updating the firmware. From this, it appears that these machines are now able to accept 6-core Xeons as well as utilize 1333 MHz DDR3 RAM.
While this sounds all great and magical, is there anything else that changed between the two revisions of the tower? I'm asking more along the lines of physical rather than software; i.e. is a 2009 model with updated firmware inferior in any way whatsoever to a 2010?
UPDATE 2015-11-02 just to be a bit more specific, my curiosity is more around if the 4,1 and 5,1 are identical except for the upgraded firmware and new CPU/GPU options? Considering the CPU/GPU can be replaced aftermarket, I'm curious if (say) the motherboard is identical between the two revisions or were there any modifications?