What is tone of voice in UX design?
A website's tone of voice communicates how an organization feels about its message. The tone of any piece of content can be analyzed along 4 dimensions: humor, formality, respectfulness, and enthusiasm.
How would a UX designer differentiate between voice and tone?
The voice represents the company or brand, and so should remain consistent across a given digital product experience. The tone also conveys mood, but in contrast to the voice, tone is something that is contextual and varies depending on what you're writing.