Already discussed in numerous threads, from what i know about the PAL region you have a large VAT tax added to your products. Another difference is the tax in PAL is included in the price of the product meaning when you go to the store and it says 299 euro then that is what you pay. In US the tax is not included but rather tacked on to the final price at the register.
Mil. Sellers:
Wii: 25 titles 101.4 mil total avg 4 mil per title
PS3: 14 titles 28.6 mil total avg ~2 mil per title
360: 41 titles 89.8 mil total avg >2 mil per title







