Apart from the differences in the vents and the lack of a window on the cab door...and that's just for the last Espee phase.
I did my SP several years ago from a Kato undec. I had to remove the GPS antenna from the roof & fill it in flat, remove the lower horizontal handrail above the inverter boxes, added a black decal for the door window, and added small triangular panel on the right side rear of the long hood under the wing (not sure what it is, maybe someone can chime in there). I didn't mess with the vents, they were 'close enough' for me.
The SD75M was easier -- I added the blower panel on the right side of the long hood, and don't remember any other changes there.
I've got another undec of each waiting in the wings for similar treatment. Maybe I should start them, so Kato would then be sure to announce them. . . .