Grid mode cuts the picture into 1 to 10 rows and columns of equal pieces. Instagram mode cuts 1:1, 4:5 or 3:4 tiles three to a row and numbers them in posting order, so they line up into one picture on your profile.
Poster mode lays the picture across several A4 sheets with a 5 mm overlap for gluing and saves them as a single PDF ready for a home printer.

