These datasets are character vectors defining PostScript procedure code for setting the color in output from the PostScript printer driver. They are the same except that ps.setcolor.hsb uses the sethsbcolor operator in PostScript and ps.setcolor.rgb uses the setrgbcolor operator.
Each procedure expects an integer on the PostScript stack. The integer is used to index (starting at 1) into the Colors array to get the color specification. If the resulting color specification is a single number, then it should be interpreted as an explicit gray level value (0=black to 1=white). If the color specification is not a single number, it will be interpreted according to the appropriate color model (RGB or HSB).