Built into every CPU is the ability to address RAM memory. To address memory, there are a certain amount of wires on the CPU that are dedicated to talking to the memory. Today, it is 32 or 64 bits.
x86 is a 32 bit processor.
x64 is a 64 bit processor.
RAM limitations
A 32 bit processor can store 232 = 4,294,967,296 values (about 4 GB). Therefore 32 bit CPUs can’t address more than 4 GB of RAM.
A 64 bit processor can store 264 = 18,446,744,073,709,551,616 (about 17 billion GB) values. Therefore, 64 bit gives more memory. Even though the a 64 bit processor can support billions of GB of RAM, the operating system will have a a maximum supported value.
Furthermore, 32 bit applications on a 64 bit system will only be able to use up to 4 GB of RAM.
Software compatibility
Software must be compatible with the bit version of Windows. For example, if you’re on a 32 bit operating system, don’t even think about trying to run a 64 bit version of software. You’ll get an error or the software will just quit working. Most 64 bit operating systems may be able to run both 32 bit and 64 bit versions of software.
In your Windows file explorer, on the C drive you may see you have a “Program Files” folder and “Program Files (x86)” folder. “Program Files” is for 64 bit programs and “Program Files (x86)” is for 32 bit programs.
Additionally drivers are specific to the OS version (32 or 64 bit).
