Hue is the term used to describe basic color. Blue, red, and green are all hues. White light passing through a prism is broken up into the spectrum of the rainbow composed of a variety of hues. The basic hues evident in this process are often referred to as spectral hues and these can be used to generate a progression of interstitial hues to fill in between the evident hues. Thus brilliant colors are more intense than are light pastels.
Luminosity is a measure of relative lightness or darkness of a color.
Color can be matched against a gray scale to make this measurement. One would expect, for example, that most shades of yellow are lighter than most shades of red. One obvious way to look at color, given two sets of primitives each with three elements, is as an ordered triple in Euclidean three-space. Indeed, that is how color maps are set up in contemporary software such as Netscape, Microsoft Office, and so forth. The result is a square or rectangle with vertical strips of color corresponding in order to the pattern on the color wheel.