A UX designer is concerned with the entire process of acquiring and integrating a product, including aspects of branding, design, usability and function. It is a story that begins before the device is even in the user's hands.
 
User interface (UI) design is the process designers use to build interfaces in software or computerized devices, focusing on looks or style. Designers aim to create interfaces which users find easy to use and pleasurable. UI design refers to graphical user interfaces and other forms—e.g., voice-controlled interfaces.
 
User Interface Design is important because it can make or break your customer base. It creates fewer problems, increases user involvement, perfects functionality and creates a strong link between your customers and your website.