Willamette Core, the first Pentium 4. Running at speed 1.4g and above, exceeding Pentium 3 speeds. Known to lose to it's competition in almost every benchmark.
A = Northwood Core, features a .13micron process, 400fsb and 512k cache. Big improvement over the old Willamette Core.
B = Northwood Core with faster bus speeds up to 533mhz.
C = Northwood Core running up to 800mhz fsb. 3.06 and above featured the technology "HyperThreading", which decrease lag from multiple heavy processes.
E = Prescott Core, featuring a .09micron process, HyperThreading and double the cache (the current ideal intel performance cpu of this generation; able to go up to 4.2ghz and higher; although suffers compared to the Northwood in last generation gaming, it is already winning battles against the Northwood in Doom 3 because of it's increase in cache and expect to beat the Northwood in future games like Half Life 2 and even Unreal 3; expect heating problems but let's hope intel fixes this in the future).
EE = Gallatin Core, modified Northwood with 2.5mb of total cache! (known as "Extreme Edition" to many people; because of it's high amount of cache, it does well in power-hungry games and is also mistaken for a prescott
, however). Future EE will be based of the Prescott. Recommended for intel fan/gamers.