The difference is size and influence of the rebate.
As a Corporation, when you offer rebates to AIBs and OEMs which don't have much cash to begin with to buy 95% of their CPU-based products to get a huge discount, that means most of the allocated budget for each line of products will be leaving any other competing components outside as the other supplier can't match the discounted price, even if doing the same. This is the equivalent of a poker match, when you go "all in" and the other party can't match you. Even Poker has rules about that. In this case Intel essentially "cashed out" AMD from even playing the round with OEMs and AIBs. This is what baffles me. This basically will set a very dangerous precedent for Companies with a lot of cash around that can easily sell at a loss until they leave competitors outside; this is also really hard to prove via accounting alone (maybe how Intel is getting away with it). Now, this is important for the CPU market specifically, as X86+Microsoft is like 95% of it in home and office computing. As always, it'll depend on the market.
Regards.