What is the difference between 32-bit and 64-bit on an Ubuntu machine?

Answer 1

64 bit is recommend if you have a 64 bit processor because 64 bit is usually better at multitasking. Also if you have over a certain amount of ram a 32 bit system cannot access it all. You will most likely not notice much difference between them.

Technically 32bit means that chuncks of data are stored in files that are sized in 32 bit groups 64 bit just uses 64 bit groups.

Answer 2

32-bit and 64-bit refer to the processor and operating system's ability to address memory. 32-bit processors can address a maximum of 4 GB of memory (because of the allocation of device resources, you'll actually see slightly less than this in the operating system. 64-bit processors (when combined with an appropriate chipset) can address a theoretical 16.8 million terabytes of RAM!

What the 64-bit version of Ubuntu does is allow the use of this potential. Running a 32-bit operating system on a 64-bit processor makes the system behave like a traditional 32-bit processor. From a user's perspective, the difference between the 32-bit and the 64-bit version, unlike in Windows, is negligible. With the exception of some proprietary applications (a 64-bit Flash player is in alpha; Java 1.7 should be released sometime this year), all the applications are 64-bit.