I’ve often had a hard time differentiating the two of user experience (UX) and user interface (UI), much less putting it into words. This real-world example illustrates the simple difference between the two.
This is certainly not a new graphic, but I have cropped it just to focus on the UX/UI portion of it.
You can see more at User Experience vs. User Interface Infographic as Cereal from usabilitycounts