computers process instructions in binary format. Each bit is capable of processing one binary instruction (zero or one) per clock cycle. Most of the PCs that are currently on the market have 32-bit processors, meaning that they can process 32 binary instructions per clock cycle.
Since 64-bit systems can process twice as many instructions per second as a comparable 32-bit system, 64-bit systems are definitely faster than their 32-bit counterparts. Perhaps the most significant difference between a 32-bit and a 64-bit system is the amount of memory that they support.
The fact that 32-bit systems only have 32-bits of data to work with means that they can only address up to 4 GB of RAM. A 64-bit system on the other hand could theoretically address up to 16 exabytes of RAM (That’s over 16,000,000 GB of RAM). In reality though, there are few, if any, 64-bit systems that support 16 exabytes of RAM. Building a machine that supports that much memory would be extraordinarily expensive. To counter this cost, many manufacturers impose RAM address space limits that fall somewhere between the 4 GB limit of 32-bit machines and the theoretical 16 exabytes that a 64-bit system should be capable of addressing. Most existing 64-bit systems limit physical RAM to somewhere between 8 GB and 256 TB.