Size is not the difference that matters — the fabric is. The small cotton one reads as a bag, goes to a gallery and a long walk, and washes in a machine, which almost nothing else does. The Lighten Up is water-repellent technical fabric, wipes clean rather than absorbing a spill, and holds a weekend, but it reads as travel gear and will not dress up. Buy the small one if it is going out with you. Buy the grand one if it is going somewhere with you.
Neither is pictured, and that is deliberate
Vera Bradley publishes one photograph per pattern, and the pattern is the product. Neither of the patterns these listings sell is in the current catalogue, so showing another one would be showing a different bag. The listing's own photographs are the honest place to look.
The one thing a backpack costs you
Access. Anything in a backpack requires taking it off, which is why neither of these replaces a crossbody for a day of trains and tickets. They buy you both hands and charge you the reach.