difference between intel core 2 extreme and quad?

i tried reading about it, but i think itd be a lot easier and straightforward if somebody told me the difference between an intel core 2 extreme and an intel core 2 quad?

 

Core 2 Extreme: 2 cores on 1 die, unlocked clock multiplier.

Core 2 Quad: 4 cores on 2 dies, locked clock multiplier.

 

but when i looked here, http://en.wikipedia.org/wiki/Intel_Core_microarchitecture#Desktops, it says that the core 2 extreme has 4 cores.

and what do you mean by dies?

 

Conroe XE Core 2 Extreme: 2 cores

Kentsfield Core 2 Extreme: 4 cores

Which one did you mean?

You can find out what a die is yourself.