Pentium III Katmai
These were the original P3 CPUs. Like all P3 processors, these processors use a 32Kbyte L1 cache. These processors have a .25 micron die and an external 512KB of L2 Cache running at 1/2 the core speed. The external L2 cache meant that they used only the Slot1 interface. They operated on a 100MHz FSB at speeds of 450, 500, 550, and 600MHz.

Pentium III Katmai B
These were the second version of the P3 to be released, and offered no new features except that they opperated on a 133MHz FSB. Again, they were only Slot1. They were availble in speeds of 533MHz and 600MHz.

Pentium III Coppermine E
These processors added the Intel SSE instructions to the processors, along with 256k of on-die L2 cache. This on-die L2 cache meant that they were able to be run in both Slot1, and Socket370 format. Despite the name, these chips do not use copper interconnects, they still use aluminum. They still used 0.25 micron fabrication and operated at speeds of 500 and 550MHz.

Pentium III Coppermine E
These chips use the same core as the original Coppermines, but they are made using a 0.18 micron process which allows them to reach higher frequencies. They are available in 600, 650, 700, 750, 800, and 850 frequencies.

Pentium III Coppermine EB
These chips used the same core as the P3 E's, but were able to operate on a 133MHz FSB. This chips are specifically for socket370 format, with the exception of the 1000EB and 1133EB They are available in 533, 600, 667, 733, 800, 866, 900, 1000, and 1133MHz frequencies.

Celeron A
Celeron processors are Intel's budget line. The first Celerons operated on a 66MHz bus and had no L2 cache. These had miserable performance and were soon discontinued. They used a 0.25 micron process, Socket370 and Slot1 interface and were available in speeds of 266, 300 and 333MHz.

Celeron
These chips are what replaced the Celeron A line. They feature a 128Kbyte L2 cache. These chips come in speeds of 366, 400, 433, 466, 500, and 533MHz.

Celeron II
These chips are similar to the Celerons, but they have a FCPGA design for Socket370 interfaces, and use the Coppermine core at a 0.18 micron. They only have 128kbytes of L2 cache, and can only operate on a 66MHz FSB. They are available in speeds of 533, 566, 600, 633, and 700MHz.

Athlon
This was AMD's first and only Slot1 interface CPU, which was originally code named the K7. This core features a 128kbyte L1 cache, 4X as large as Intel's fastest processors. This processor used a SECC format because its L2 cache wasn't on die. A 512kbyte L2 cache was mounted on the SECC, which operated at speeds of 1/2, 2/5, or 1/3 of the core frequency, depending on the processor, and the SRAM available during production. The fastest SRAM that was ever used was 350MHz. This wasn't a problem, but as the frequencies increased to over 700MHz, it became a bottleneck. Currently no more Athlon processors are being produced, but there are many still on the market. All AMD production has shifted to the Thunderbird and Duron line. Notably, this was the first retail processor to reach the 1GHz mark. They available speeds were 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, and 1000MHz.

Athlon (Enhanced/Thunderbird)
This is the current highest performance processor line from AMD. It is based on the Athlon core, with 256kbytes of integrated L2 cache that can operate at full core frequency. It was originally code named Thunderbird, but now sells as just Athlon, because the original Athlon is no longer produced. It was the first processor to use copper interconnects, and is currently being sold using both copper and aluminum. It was originally designed for only SocketA intfaces, but some SlotA versions are being sold to OEMs until their SlotA supply of motherboards runs out. This chip is currently available in speeds of 700, 750, 800, 850, 900, 950, 1000, and soon to be 1100MHz.

Duron
Code named Spitfire, the Duron is AMD's current budget line. It is exactly the same as the Thunderbird processor, except it features only 64Kbytes of on die L2 cache. This chip is only available in speeds of 600, 650 and 700MHz.