"Program Files" .vs. "Program Files (x86)"

#1
What is the difference between these two folders please? I have some programs I need to manually install and give shortcuts to so wonderin g where to place them.
 
#3
I guess I can use %@exetype[] to see if it's 32 or 64 bit. Actually it doesn't return anything if it's 32 or 64 bit. Anyone know what I can use to see if a .EXE is 32 or 64 bit?