You might want to download an application for your computer from some website. There you will find two options in front of you, Whether to download the 32-bit version or the 64-bit version.
The terms 32 bit and 64 bit refer to the size of the memory addresses and general purpose registers that an application uses. A 64-bit application requires a 64-bit processor and a 64-bit operating system. However, most 64 bit systems are also capable of running 32-bit applications in a compatibility mode.
The Memory address is the most important difference between 32-bit and 64-bit applications. Use of 64-bit addresses allows a process to address a theoretical maximum of 2 raised to 64 i.e. 16 exabytes of memory, This is a dramatic increase from the 2 raised to 32 i.e. 4 gigabytes of physical memory that a 32 process is limited.
Because of the above-mentioned difference, A 64-bit Application may be faster because it can keep more data in memory, reducing slow disk access. The expanded 64-bit address size also makes memory-mapped files more practical, which may allow for more efficient file access than traditional APIs. In addition, 64-bit arithmetic may be faster because of the larger register size.
On the other hand, 64-bit memory addresses mean that all pointers require twice as much memory to store. For data structures that employ pointers or references, this means that the same data structure requires more memory in a 64-bit application than in a 32-bit application.
More important, any given system has the same fixed-size processor cache whether running 32-bit or 64-bit applications. Because the 64-bit data structures are larger, less of them fit in cache, so there are more likely to be cache misses in which the processor must wait for values to be accessed from main memory or higher cache levels.
Because some aspects of a 64-bit application lead to higher performance and others lead to lower performance, some codes may run faster as 32-bit while others run faster as 64-bit.