In Progressive scan the image is displayed on the screen by scanning each line also called as row of pixels in a sequential order. While in Interlaced it happens in an alternate order. The image lines or pixel rows are scanned in numerical order (1,2,3) down the screen from top to bottom in progressive scan. And in interlaced scan the order is alternate lines or rows 1,3,5, etc... followed by lines or rows 2,4,6.