480i stands for a resolution of 704480 that is interlaced, and 480p stands for a resolution of 704480 that is progressive. Interlaced resolutions are made up of 60 half frames per second, while progressive resolutions are made up of 60 full frames per second.
Each woven frame has stripes that alternate between showing the picture and being blank. The stripes that aren’t blank add up to half of a frame. To save data bandwidth, interlaced resolutions are used.
The resolution of 480 is called “standard definition,” while the resolutions of 720 and 1080 are called “high definition.” The terms progressive scan and interlaced also apply to resolutions in high definition.