I would say some changes were made to base chip on the colaboration and perhaps those modifications are exclusive to Sony. Possibly MS will have other modifications exclusive to them. But in the end performance will be near.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"