>>>>FOR BOTH EXAMPLES, JUST ROLL THE CURSOR OVER EACH PICTURE AND OUT TO SEE THE DIFFERENCE <<<<

When seen on a smaller screen (see example below), the difference is not that noticeable, but when displayed on a large scale screen (HDTV for instance), as in example 2, the gain in quality seems obvious.

EXAMPLE 1
STANDARD DEFINITION = DVD quality (576px resolution in heigth*)
VS
DOWNSCALED FULL HD = Blu-Ray quality (from 1080px 576 pixels of resolution)

*Note that resolution is calculated in the number of vertical lines/pixels the images is composed of

>>>>FOR BOTH EXAMPLES, JUST ROLL THE CURSOR OVER EACH PICTURE AND OUT TO SEE THE DIFFERENCE <<<<

EXAMPLE 2
UPSCALED STANDARD DEFINITION (from 576px to 1080px resolution)
VS
NATIVE FULL HD at 1080 pixels of resolution

}}}} The larger the screen, the more your DVD (which contains less information)will get upscaled, {{{{
}}}} whereas the Blu-Ray (=HD) looks crisper as it contains more details. {{{{