From my initial research, the newer model 103b is supposed to have LESS shutter lag. It also has a sharper lens. (It is very sharp!) The vintage film sim was also a bit more magenta in the older model. (You can’t use the older sim in the newer camera)
Some folks like the old model for the old vintage sim and the more (edge) blurred images.
For anyone considering buying one. It is frustratingly (but endearingly) obtuse to use (see my earlier posts above). You can’t change sims without plugging into a computer and dragging the .bin file onto the micro SD card. I tried to do it using an iPhone, but the card didn’t show up in the files app. And the simple process of turning it on as well as the shutter lag is infuriating. But fun! Ha
Pro tip: I made a “BIN” folder on the SD card and stashed the 3 film sims in there. This way, I can copy-drag a .bin from that folder into the root directory without having to search my computer drive for the files. (Note that initializing the new .bin erases the .bin file from the SD root directory. But stashing them in a discreet folder keeps them alive and available on the SD.)