X86 and x64

It's at the processor level, actually.

Generally, you need a 64-bit processor to use 64-bit software; after that, with a 64-bit processor, you can normally use software in either 32 or 64 bits.

The idea is that with a 32-bit system, only 3GB of RAM is recognized, while with a 64-bit system, you can have more than 3GB of RAM recognized.

64-bit is supposed to be better, but you need to have the right processor, the operating system in the correct version, and then have software that works well in 64 bits.

Well, you need a processor that supports 64-bit to use 64-bit, and a 32-bit processor to use 32-bit.

In terms of human vision?

Your applications are supposed to run faster because your processor performs larger operations, working on 64 bits instead of 32. So depending on the software you use, yes, the speed can change. If your software is power-hungry, then 64-bit is better. It seems to be especially useful for photo editing, video processing, and gaming.

Here are some links that should explain it correctly:

https://www.generation-nt.com/x64-emt64-amd64-os64-bit-xp64-64-vista64-xp64bits-vista64bits-article-68608-4.html

https://fr.wikipedia.org/wiki/Processeur_64_bits

https://support.microsoft.com/en-us/windows?ui=en-US&rs=en-001&ad=US

What processor is needed?

And is there a difference in the way humans perceive vision?

None... Just a "vision" of your OS on your processor. With a 64-bit processor, you can install a 64-bit (or 32-bit) OS that performs better than a 32-bit one. But the reverse is not possible.