I will give a few explanations:
1) x32 operating systems are designed for 32-bit processors, x64, respectively, for 64-bit. Nowadays, 64-bit operating systems are installed on new computers.
2) 64-bit systems support a larger amount of RAM, unlike 32-bit, which are only up to 4GB.
3) The software can also be developed for x64 or x32 bit systems. Drivers, respectively, are also different.
4) A processor with support for x64 systems runs faster on them than on x32.
The x86 operating system is the x32 operating system, that is, 32-bit.