The x64 architecture is a backward compatible extension of x86. It provides a legacy 32-bit mode and a new 64-bit mode that are the same as x86.

The term "x64" includes both AMD 64 and Intel 64. The instruction sets are the same.

Modern x86-based laptops and desktops, also referred to as "x86-64", have 64-bit CPUs instead of 32-bits. x64 usually refers to the hardware, not the operating system.