Well, the whole of the f minor sonata is a lot to learn in comparison with the relatively short first movement of the Italian Concerto. In any case, the Beethoven sonata has a challenging last movement if your technique isn't fairly polished - the Bach, save one or two awkward spots, isn't too difficult technically. Also, the Bach involves A LOT of repetition.
Evdiently, the entire opening 'tutti' repeats, note-for-note, to close the movement, and several of the sequences are repeated immediately but varied using ornamentation. As such, it is probably easier to memorize, and there is considerably less music to learn.
The benefit is that both pieces are wonderful and acceptable concert-level repertoire. Good luck if and when you decide to tackle one of these...or maybe both!