People high in hierarchical world belief see the world as full of differences that matter [..] You might imagine that, to them, the world looks full of big, bold black lines. The opposite view—held by people low in this belief—tends to perceive differences as superficial and even silly. For individuals with this perspective, the world is mostly dotted lines or shades of gray.
This conflates two distinct things: the belief that things differ (e.g. blue is different from red), and the belief that there are clear and unambiguous distinctions between categories (on the color spectrum, where exactly does blue transition to red?)
It seems one side argues there is a clear, objective line between blue and red, while the other argues blue and red are the same color.