x86 refers to any processor that is instruction-compatible with the
Intel 8086 and higher. This includes the Pentium, Pentium II, Celeron,
Pentium III, Pentium 4, Pentium D, Core Duo, Core 2 Duo, Core i7, Atom,
AMD Athlon, Sempron, Athlon 64, Phenom, and Geode. In summary
32 bit type processors
x64 is often
used to refer to any x86 processor that has 64-bit extensions (x86-64).
These include the AMD Athlon 64, late models of the Pentium 4, Pentium
D, Core 2 Duo, Phenom, and certain Geode processors. In summary
64 bit type processors
x32 is a retcon of the x64 term to apply to either 32-bit only processors or programs.
Microsoft publishes KB946765 which details the main differences between
32-bit and 64-bit Windows Vista, which mainly relate to memory
accessibility, memory management, and enhanced security features, as
listed in table below.
Architecture |
Windows Vista, 32-bit versions |
Windows Vista, 64-bit versions |
System requirements |
1-gigahertz (GHz) 32-bit (x86) processor or 64-bit (x64) processor,
512 MB of RAM |
1-GHz 64-bit (x64) processor, 1 GB of RAM (4 GB recommended)
|
Memory access |
A 32-bit version of Windows Vista can access up to 4 GB of RAM. |
A 64-bit version of Windows Vista can access from 1 GB of RAM to more than 128 GB of RAM. |
Memory access per edition |
All 32-bit versions of Windows Vista can access up to 4 GB of RAM. |
Windows Vista Home Basic – 8 GB of RAM
Windows Vista Home Premium – 16 GB of RAM
Windows Vista Business – 128 GB of RAM or more
Windows Vista Enterprise – 128 GB of RAM or more
Windows Vista Ultimate – 128 GB of RAM or more |
DEP |
32-bit versions of Windows Vista use a software-based version of DEP. |
64-bit versions of Windows Vista support hardware-backed DEP. |
Kernel Patch Protection (PatchGuard) |
This feature is not available in 32-bit versions of Windows Vista. |
This feature is available in 64-bit versions of Windows Vista.
Kernel Patch Protection helps prevent a malicious program from
updating the Windows
Vista kernel. This feature works by helping to prevent a kernel-mode
driver from extending or replacing other kernel services. Also, this
feature helps prevent third-party programs from updating (patching) any
part of the kernel. |
Driver signing |
Unsigned drivers may be used with 32-bit versions of Windows Vista. |
64-bit versions of Windows Vista require that all device drivers be digitally signed by the developer. |
32-bit driver support |
32-bit versions of Windows Vista support 32-bit drivers that are designed for Windows Vista. |
64-bit versions of Windows Vista do not support 32-bit device drivers. |
16-bit program support |
32-bit versions of Windows Vista support 16-bit programs, in part. |
64-bit versions of Windows Vista do not support 16-bit programs. |