Quote - What's the difference between a picture that's 1200x1200 pixels, 24bit, 72dpi or a picture 1200x1200 pixels, 24bit, 300dpi? Is there more information in the picture or is it just a switch?

There is absolutely no difference. Many people don't understand what dpi even means in CG so they start thinking a higher dpi means higher quality. This is just not true. 72 dpi means that when printed (on paper) the printer will use 72 dots per inch to print the image. 300 means it will use 300. In both cases the size of the image printed will change, but always at the same quality of 1200x1200 points.

ie a 1200x1200, 300 dpi pic will print at 1200/300 or 4 inches by 4 inches. A 72 dpi one at 1200/72 or 16 x 16.

The only way to get higher detail is to increase the rez itself, dpi does nothing.