I see some slight differences in the shape of the needle slot and the tension spring. Mainly it amounts to Necchi spent a little more money on making theirs. It's possible the other one was replaced at some point with a more generic one. Both look like pretty typical class 15 bobbin cases. There were a few styles made over the years, you do have to be careful you have the right class 15 bobbin case.
Sew-Classic.com offers a good explanation of the differences.
Rodney