UI or GUI refers to User Interface (Graphical User Interface). UI design is the visual elements, screens, or the pages you interact with. Meanwhile, UX or GUX refers to User Experience (Graphical User Experience). UX is the experience that the users have when they interact with a particular product or services. Both terms are generally used together considering the business goals and intent of undertaking a design process to improve your website/application qualitatively. However, they refer to different elements of web design.