The ONLY difference is they have an unlocked multiplier, they might also be able to tollerate a bit more heat.
They are not worth your money, and i dont recommend getting one
The performance is great, but its hardly better than a Q6600 which is only £150 compared to £600 extreme chip, and the new 45nm quads will outperform a Qx6850.
The only thing different is the multiplier, and this does not affect perfromance what so ever at stock speeds.
Like Taylor said, the only reason to get an EE edition is if you want more overclocking options. An unlocked multiplier allows you to keep the FSB at a lower level.
a friend of mine cant get his QX6850 from 3.0 GHz to 4 GHz stabley,