WHAT IS THE DIFFERENCE BETWEEN OS 32 BIT AND OS 64 BIT?

There are many differences between the OS 32 Bit and OS 64 bit but one of the major difference is that Windows 32 bit can only address 4 GIG of memory RAM, where as the 64 bit can handle more RAM and used it better as well. If your PC has 4 GIG Ram for instance, its better to move over to 64 bit. 
      Simply you can access large amount of random access memory using 64 bit operating system than a 32 bit operating system . . .