There is actually a concept of whiteness when it comes to white shirts. The color white has a range of shades. Many of the dress shirts sold at mass retailers for suits tend to have a bluish tint. They look clean and sharp, but the natural color of the cotton is lost. This is because they are produced using chemicals called fluorescent whitening agents.
Shuttle notes shirts are made without the use of fluorescent whitening agents, aiming for a natural whiteness. They fit well with jeans and jacket styles.