Some printers may be connected to windows by several different drivers. The HP printers can do intermixed raster fills and vector drawing. Line thickness through color mapping will work, but all brush and bitmap fills become solid fills. These options let you change the color used when printing from that used on-screen. You would want to print these white lines as black on the printer.
Some printers try to print color as grey-scale at higher resolutions.
Summary Hopefully, the above will explain why there is such a multitude of width and thickness options in FastCAD, and in which situations they might be of some use. Many people will use the width property for line widths, with all boxes unchecked, and never become involved with color mapping. This approach is much less complex. For those customers with high volume printing needs where printing speed is critical, these options provide viable solutions worth the added complexity.