They are almost completely content-identical, from my understanding. Given how far beyond 10 million sales are going, I think we can count on the fact that there's 10 million unique buyers, just like we can with Pokemon.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.







