UX designers and UI designers have different backgrounds, focus, and skill sets. While it is possible for a UX designer to do UI design, it is not typically the focus of their work. A UX designer’s job is to think about the user experience and design the user interface to make the user’s experience as positive and efficient as possible. A UI designer’s job is to create the look and feel of the user interface, as well as the underlying structure and functionality.
Often times, a UX designer will work closely with a UI designer to create a cohesive design. While it is possible for a UX designer to do UI design, it is not typically their focus, and the two disciplines are usually carried out by different professionals.