The limited print editions refer to the total number of prints that will ever be done of that one image. For example an edition of 150 prints may come in three different sizes but there will only ever be 150 of that particular image ever printed.
Petite prints are all in a square format. They are smaller, and each print comes in the same size, designed so they can be grouped together on your wall. All of the Petite prints come in the smallest size which is 245 x 245mm for the image and 305 x 320mm for the paper.