HP vs Brother Printer DPI Question

[idahosurge]

I need a new printer, I currently have a Brother laserjet HL-2070N at home and a HP laserjet 1020 at work. The when printing maps (MSN maps, etc.) and logos, etc. HP prints darker and print quality wise it seems just as good as the Brother, but the Brother is rated at "up to 2400*600 dpi" while the HP is rated at "600*600 dpi".

I am looking at this Brother
http://www.newegg.com/Product/Product.aspx?Item=N82E16828113690

and this HP
http://www.newegg.com/Product/Product.aspx?Item=N82E16828115635

again the Brother is rated at 2400*600 dpi and the HP is only 600*600 dpi, but the HP is over twice the price and that is on sale.

Both printers are black and white printers, no color.

Question 1: Does the HP print darker because it is only 600 dpi so does not print as many shades of grey as the Brother? The Brother prints sections of the map/logo lighter because it can print many more shades (lighter) of grey?

Question 2: Does the Brother really print at 2400*600 dpi or is that a marketing gimmick?