Recently, some discussions came up about 32 bit vs. 64 bit implementations of operating systems.
While I was composing a message about this topic, I realized that I did not know if there was a correct term for the number of bits supported by an operating system.
For example, various versions of Solaris and Linux have 32bit and 64bit releases. Is the distinction "architecture"? In my experience, that has referred to chip types (Intel vs. PPC). Is it a "release"? Typically, I think of a release as a version number a consistent feature set, that might run on different architectures.
Maybe it is just "architecture", after all, even though a chip family might have used several different bit sizes over time, the chips themselves are different when you jump from 32bit to 64bit.
I would use architecture.
Releases are just the specific versions of the software (or in this case entire Operating System) package.
Also, looking at the chip families, marketing will tie them together more than the technical aspects for any jump between 32bit and 64bit chips.
There is no definitive term but architecture is as good as any. By the way, it's word size, not bit size. Bit size is by definition fixed at one bit, whereas words can be any power of two. Although the smallest practical CPU I've seen is four bits.
The Solaris 10 documentation uses the phrase: "instruction set architecture".
The command for Solaris is to use:
If I have time, I will try to add examples for other operating systems.