assuming the same fore-aft and height, then there'd be no difference there.
But there would be in how all might function - if you're in the middle of the saddle rails on a 25mm setback post then you might not get back far enough on a zero - depending on the saddle rails - in the smilar situaton the adjustment will certainly be very limited in one direction, and if you wanted to try a different fore-aft, you might not be able.
If you do get back far enough then there is likelyhood that your leg might rub the post parts - depending on the post. Or the zero post might cause flaring of the saddle if it has skirts, and again, leg rubbing if it doesn't. Or a saddlebag or saddlebag attachment (as in velcro) might catch your legs/shorts and cause the dreaded 'leg fuzz' or worse, a hole.
Most road bikes come with some type of setback post, because for the avg rider with avg body dimensions, a setback gives adjustment both ways... but zeros do work well for many who try them... no black or white here