And now, we get to see the picture...
480i: What analog TV is now, just digital.(640x480)
480p: Still 480 lines, now every line, every time.
720p: 720 lines, every line, every time.(1280x720 at 24,30,50 or 60Hz)
1080i: 1080 lines, every other line refreshed at 60 Hz.(1920x1080)