They are significantly different things.
abstracting the differences between operating systems and the differences between CPU architectures?There are Windows, Linux, Mac OS like operating systems and there are Intel, AMD, Sun like CPU architectures. Java abstracts the difference between Windows, Linux, Mac OS operating systems and at the same time Java also abstract difference between Intel, AMD, Sun like CPU architectures. Java abstracts the difference between operating systems and at the same time Java also abstracts difference CPU architectures.
abstracting the differences between SET A (which is operating systems) and Set B (CPU architectures)?Java abstracts the difference between operating systems and CPU architectures.
Hope, it will helpful.