I have both (I'm a serious MJ fan) and they are good for different things. The two-handled Stella (bottom) has a zipper along the top that comes completely apart, allowing you to put things like files, books, your lunch, etc. in there (and I do).
The shoulder-strapped Sofia (top) has three separate compartments, two zipped and one that closes with a zipper, so it is lovely when you want all of your things in their own proper place, rather than one big compartment.
Both can go on the shoulder, but the Stella can also be hand-carried.
Both can also be adjusted as to the length of the straps.
I find I use the Stella more than the Sofia, as an everyday bag.