x64-based(Pertaining to the combination of a 64-bit Windows operating system and microprocessors that natively support the x86 for extended systems (x64) 64-bit instruction set. Examples include AMD Opteron and Intel Xeon with 64-bit extension technology processors)
x86-based(Pertaining to the combination of a 32-bit Windows operating system and a microprocessor that natively supports the 32-bit x86 instruction set. Examples include Intel Pentium 4, AMD Athlon and VIA C7 processors)