At first sight, website design to a viewer appears to be the visuals seen on a web page. But the fact is that a whole gamut of techniques and skills are involved in creating a web page design to give it the desired look.
So, web design is about deciding on a lot of elements such as the layout, graphics, colors, fonts, structure, content, text styles, interactive features, imagery, interface, standardized code, etc. It involves a wide range of skills and disciplines.
Professional website design is the one that maintains an appropriate balance in the different elements and ensures consistency and integrity of the design.