There are little confusing information about resolution found as 720p, 1080i, 1080p. To be simple told P means Progressive Scan, and “i” means Interlaced scan.
Progressive scan is technology in video resolution to transmit video signal from hardware to the output as full combined frame.
Progressive scanning might require more bandwidth than basic interlaced scanning, but it simplifies the transmission of video by doing away with the need for deinterlacing. It also improves video quality by sending complete frames rather than segmented parts.
One problem that can arise with progressive scanning, however, is that objects moving continuously through the camera scene, such as a car, can appear to flicker. Since each line of the image is scanned every sixtieth of a second, there is a brief gap of time between frames that does not account for objects moving unremittingly. However, modern television and computer screens overcome this problem by using a practice called pull-down sequencing, in which frames are repeated when necessary to ensure a smooth and accurate viewing experience.
There are two main flavors of high definition TV, 1080i (the i is for interlaced) and 720p (p for progressive). 1080i offers the most pixels, with a matrix of 1920×1080 pixels, while 720p has fewer pixels at 1280×720 pixels. However, the difference is made up with the frame rate, which is only 30 frames per second with 1080i, but is double that with 720p, at 60 frames per second. The total pixels displayed per second is actually very similar, with 720p offering 55 million pixels per second, while 1080 is slightly higher at 62 million pixels per second.
What does all that mean? It all depends on the type of TV you watch. 720p is better at showing pictures with plenty of motion, since the higher frame rate helps smooth any quick motion on the screen – this is better for sports or action movies. 1080i offers more detail, which is for movies with lots of images or panoramas.
The best of all is the 1080p option. It offers the best of both world, 60 frames per second at 1920 x 1080 pixels. The toal bandwidth is 124 million pixels per second, double that of 1080i. It can display any HDTV signal without any downconverting. 720p signals are upconverted, while 1080i signals only require some gently “de-interlacing” to work properly. 1080p is the perferred option is possible – its backwards compatible with all old formats, and is ready for upcoming high definition discs.