Difference between program files and program files(*86) on windows OS?

A 64 bit windows OS has 2 different but similar folders
1.Program Files - which contains 64 bit applications
2.Program Files(*86)- which contains 32 bit applications.


This is because, windows run both 32 bit and 64 bit architectural programs on 64 bit OS.
I do not know why it does not use all 64 bit programs on 64 bit OS ?


In short, 32 bit architectural programs are stored under Program Files(*86) and
64 bit architectural programs are stored under Program Files.