86x bit and 64x bit difference

Hi

x64

64-bit (aka x64) is a more "modern" architecture. 32-bit is the PC standard going back aways and will work on just about anything out there now.64-bit requires a 64-bit capable computer. However, as only 64-bit can go over 4 megabytes of RAM,

x86

x86 denotes a family of instruction set architectures[2] based on the Intel 8086 CPU. The 8086 was introduced in 1978 as a fully 16-bit extension of Intel's 8-bit based 8080 microprocessor, with memory segmentation as a solution for addressing a byte-wide memory larger than the 64 KB that can be covered by a 16-bit address. The term x86 derived from the fact that early successors to the 8086 also had names ending with "86", with successive digits inserted between the "80" and "86" (e.g. 80286, 80386). Many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility.

Even though you are using a 64 bit system, many applications are still 32 bit and they are stored in Program Files (x86). This is normal.