Brand guidelines are rules a business sets for presenting itself to the public, including its logo, colours, fonts, voice, tone, and design. Consistent branding helps customers have the same experiences when interacting with the business.
The user interface (UI) is the point of human-computer interaction and communication in a device. This can include display screens, keyboards, a mouse and the appearance of a desktop. It is also how a user interacts with an application or a website.