Art design, as its name implies, is to beautify the appearance of the website. The deeper level is to highlight the connotation of the website itself. The real meaning of the position of UI designer is not art design (or just "beautification" work). Accurately speaking, UI designer is a technical position rather than an artistic position.
To do UI design, art design is only a part of visual design, and UI also includes operation logic and user experience. For example, when developing Android interface design, we will use AndroidUI design, including the overall design of the whole interface, buttons, icons, layout and so on. If you want to make the interface look good, you can't do without art.
If you want to design a UI, designers don't have to write Java code, but they must know Java and know what they want to achieve. Because only by understanding the programmer's code can you know what kind of UI layout elements you need. Artists don't need to know Java language, they just need to follow the footsteps of designers and provide suitable pictures.
As a UI designer, you need to deal with mainstream design patterns in the market, understand HTML, CSS, Javascript and XML technologies, flexibly use UI design tools and UI frameworks, and understand UI threads and UI design specifications. The artist's job is to cut out the picture and make the required picture material.
UI designs the overall layout, and artists beautify the picture. If the UI is a designer, then the artist is an art beautifier, so we can't confuse them.