Digital BW, The Print

Could someone describe to me what is going on tonally when one chooses either 2.2 or 
1.8 gama setting in a given print driver? I know I should know technically what is going on 
here but  sheepishly I admit that I don't.

I know that when I print BO greyscale out of my 10K I have quite smooth transitions with 
2.2 and unacceptable results with 1.8.

I know that when using the greyscale Cone PIezzotones out of a 1200 or 1280 the 
recommended gamma setting is 1.8 with their ICC profiles.

I also know that when printing out of QTR on my 1200 with Piezzotones if I choose 2.2 
gamma I get excellent results by just using that as my profile, even without linearizaton or 
a custom made ICC profile for that media ink combinaton. I assume the difference is the 
way the driver maps the tonal scale and thus where the ink is laid down from a particuar 
area of the scale. Right?

John