Here is the picture of my 8GB and my friend 4GB, I noticed he has some kind of dots pattern on his screen and mine doesn't. I didn't see any of that on my screen, and it looks so smooth. The photo of the 8GB was taken even closer than the 4GB.

here it is my 8GB



and here is the 4GB



or maybe he has a faulty product?

some more to compare

8GB


4GB

The dots are visible in all of the photos. The lighting makes them much more prominent in the 4GB photos (top and bottom black bands clearly show the red dots) and less prominent but still visible in the 8GB photos (easiest to spot as white dots over the grey band on the 8GB screen). The dots appear to be part of the touch sensors in the Balda touchscreen.

The 'dots' are unavoidable, as they represent an integral part of the touch-sensitive part of the display. Their visibility largely depends on viewing angle, backlight setting and ambient light.
BTW displays in 4gb and 8gb phones are same P/N, don't ask how I found that out..