Joffrey and Ramsay being essentially the same is a bit of an oversimplification isn't it?
Joffrey was just a spoiled little shit who because the rules more or less didn't apply to him didn't feel a need to bother with rules. There was no method to his madness. No aim to his cruelty except cruelty. And in most cases it was those around him performing the cruelty at his behest and under threat of the force others would bring to bear.
Ramsay on the other hand has a method. The cruelty while he enjoys it isn't the point in and of itself. "I win when you beg me to cut off your finger." He serves his father and seeks his approval. Ramsay handles his own affairs and the other tasks set to him. Ramsay has had to earn his keep.
Joffrey could not create Reek. Joffrey wouldn't have the patience.