Apparently, the conceptual differences between hues, saturation, lightness, tints, shades, and tones can be described by using a color sphere.
http://en.wikipedia.org/wiki/
Hue: what we think about when we generally think of colors; lines of longitude along the sphere's equator (as on a color wheel) represent different colors without lightening or darkening.
Lightness: lines of latitude; for a specific hue at a point on the sphere's equator, moving south along a line of longitude toward the south pole will make the hue progressively darker, until pure black is reached at the south pole; moving north along a line of longitude toward the north pole will make the hue progressively lighter, until pure white is reached at the north pole.
Saturation: a point on a line from the center of the sphere to a point on the sphere's surface; this line represents a color continuum between a neutral gray (the center of the sphere) and a fully saturated color on the surface of the sphere. I think in this scheme, lessening a color's saturation means adding gray, until finally fully gray is reached at the center.
Nuance: colors of the same lightness (latitude) and saturation (radius), but different hues (longitude). This would be like scalping the earth along a line of latitude, then using the radius to draw a circle on the the exposed part. All the colors (hues) on that circle at the various lines of longitude would be nuances of each other, I think. Another way to think about this would be: the amount of white/black (lightness) and gray (saturation) is fixed and applied to all the hues equally.
Tints and Shades: colors of the same hue (longitude) and saturation (radius), but different lightness and darkness (latitude). This would be like discarding all of the earth save a tiny slice representing the particular longitudinal line from pole to pole, then using the radius to draw a half-circle on that tiny slice. The colors on that half-circle would all be of the same hue and saturation, but they would differ in lightness and darkness. Another way to think about this would be: the amount of gray (saturation) and the color is fixed, but not the amount of white/black (lightness).
Tones: colors of the same hue (latitude) and lightness (longitude), but differing in saturation (radius). This would be a line from a point on the surface of the earth to the center of the earth; the colors on the line would all be the same hue and lightness, but would get progressively grayer until they became pure gray at the center of the earth. Another way to think about this would be: the amount of white/black is fixed (lightness) as well as the color, but not the amount of gray.
The above links give pictures and such.
Another fun resource (not a color sphere, but a color wheel): http://colorschemedesigner.
