What is 32-bit and 64-bit?

The number of bits in a processor refers to the size of the data types that it handles and the size of its registry. 32-bit and 64 refers to size of the Operating System, that tells how much information CPU can handle (processor)

• 32-bit
• 64-bit

• 32-bit processor 

The 32-bit processor was the primary processor used in all computers until the early 1990s. Intel Pentium processors and early AMD processors were of 32-bit, which means the operating system and software work with data units that are 32 bits wide. Windows 95, 98, and XP are all 32-bit operating systems.Also a computer with a 32-bit processor cannot have a 64-bit version of an operating system installed. It can only have a 32-bit version of an operating system installed.

•  64-bit processor

A 64-bit processor is capable of storing 264 computational values, including memory addresses, which means it's able to access over four billion times as much physical memory than a 32-bit processor.Microsoft released a 64-bit version of Windows XP to be used on computers with a 64-bit processor. Windows Vista, Windows 7, and Windows 8 also come in 64-bit versions. Other software has been developed that is designed to run on a 64-bit computer, which are 64-bit based as well, in that they work with data units that are 64 bits wide.

Difference between them 

• A big difference between 32-bit processors and 64-bit processors is the number of calculations per second they can perform, which affects the speed at which they can complete tasks. 64-bit processors can come in dual-core, quad-core, six-core, and eight-core versions. Multiple cores allow for an increased number of calculations per second that can be performed more faster, which can increase the processing power and help make a computer run faster. Software programs that require many calculations to function smoothly can operate faster and more efficiently on the multi-core 64-bit processors. 
• 32-bit processors and 64-bit processors is the maximum amount RAM that is supported. 32-bit computers support a maximum of 4 GB of memory, whereas 64-bit CPUs can address a theoretical maximum of 18 EB(Exabyte). 
• 64-bit machines can process much more information at once, making them more powerful. If you have a 32-bit processor, you must also install the 32-bit Windows. While a 64-bit processor is compatible with 32-bit versions of Windows, you'll have to run 64-bit Windows to take full advantage of the CPU's benefits.