Portable Apps and 32/64 bit downloads

I am just wondering if I download a portable app (like a zip program) to my USB stick, I understand that this means I can run this app without installing it on any pc straight from my stick.

I wonder though why some apps, e.g. PeaZip http://peazip.sourceforge.net/ offer a choice of portable files either 32 bit or 64 bit? If I don't know which pc I am working on in the future and intend to use it via my stick what should I choose?

 

Depends on if the machine you're using has 32-bit or 64-bit Windows installed. If unsure, choose 32-bit, because those are usually 64-bit compatible thanks to WoW64.

 

thanks J_L - since I want the program to be flexible, in that case I will take 32-bit. I don't know beforehand where I may want to use the portable version in the future. I guess I could download both onto my stick