The big Xperia Z3 is shown to be 7.3mm thick, compared to 8.2mm for the Xperia Z2. It’s also more than a millimetre narrower at 72mm. These small margins should make a surprisingly big difference to the feel of the phone.
The rumoured Xperia Z3 compact, though, looks to be exactly the same size as the Z1 Compact.
Of course, these drawings could be a hoax so we’ll still be waiting to see how the phones look when they’re officially announced. But this does give us something to hope for.