What is diferent betwin 1920*1080p and 1920*1080I

Television pictures are a series of still pictures that are presented quickly to give the illusion of continuous movement.
1080p and 1080i indicate how these pictures are formed.
1080p is progressive scan. It is a format that "paints" the picture left to right, top to bottom. On older tube type screens, this would cause the top of the picture to be dimmer than the bottom, as the phosphers would fade before the next picture was painted.
1080i is interlaced scan. This format paints every other line from top to bottom, and then paints the lines it missed before moving to the next picture. This evens out the brightness.
If your TV is capable of 1080p, it is considered to be the best picture (but you probably won't see the difference).