I can see how this might be a confusing issue. I don't know the
exact meanings of the terms, but this much I do know... A
monitor with .28mm dot pitch is a sharper monitor than one with
.39mm dot pitch. A monitor is made like a television set, in the
sense that it has a fine "mesh" (put your eyes up to it), rather
like a screen door. If the wire in the mesh is .39mm
(millimeter) wide, then it is wider than .28mm wide. The
skinnier the wire mesh, the sharper the image. But, in all
honesty, I wouldn't worry terribly about it. *If it looks good
and sharp, then stick with it. *If all you have is $125 and all
you find are .39mm dot pitch VGA monitors for that price, while
there are .28mm dot pitch VGA monitors for $175 - try getting an
extra $50, but if you can't, get the .39mm dot pitch monitors.
The difference is smaller than many nit-pickers like to say.