"Wes Harrison" writes:

Well, they're both 64 bits and both use an x86-based instruction set and
both made by AMD so what exactly is the difference? Is it like the
difference between a Pentium and a Xeon?

Opterons have 3 HyperTransport channels, Athlon64/FX-51 has one.
Opterons and Athlon64 FX-51 has a 144-bit wide memory bus while
Athlon64 has a 72-bit wide memory bus. Athlon64s may appear with
smaller caches but AFAIK the only currently available one (3200+) has
1MB of L2.

*p