This settings seems to be an attempt to dig into common basic Properties of whichever printer is being used, to either check this check box, or un-check it. Since the 'Print in Grayscale' is a very common check box type setting in almost every printer's Properties, that setting will most likely always work. But the 'Color Options' and/or 'Color Themes' settings on the other hand are very likely different from one printer to another. There is likely always a default color setting though, which is likely used when the 'Print in Grayscale' setting us unchecked. The kPrintColorPalette setting likely only does something special for certain printers.
Makes me wonder if Autodesk is attempting to work with several printer manufacturers to standardize how certain common settings are specified & accessed, to make them accessible through VBA.
Other than that, I can't find any documentation or comments distinguishing differences between the two settings.
Hopefully someone from Autodesk can provide a better answer for this one.
Wesley Crihfield

(Not an Autodesk Employee)