You might notice that voice and tone are sometimes used interchangeably. However, in UX writing, these are two different notions.

We can compare brand voice to a person's character — mental and moral qualities distinctive to an individual or a product. Conversely, tone is a mood the person or product takes on in a particular context.

While the character remains constant, the mood fluctuates based on context. Every scrap of writing on a page — from body copy to button labels — contributes to the tone of voice the product uses to speak to its users. For example, a fun and casual tone can work for the onboarding copy. However, it's not appropriate for error messages or money transactions — the context here calls for a more serious and concise tone.