dr.kol
11333
There are a lot.
The main difference is that 3712 is having a case made of two parts while 5712 a case made of three parts. In the latter you get access to the movement by opening the case back but in the 3712 the whole case must be opened from the lugs. Just lie the port hole of a ship. The case design of 3712 is the one designed by Gerald Genta.
Some other differences:
3712/1 5712/1
Crown Push down Screw down
Case width 42 mm 43 mm
Case thickness 8.37 mm 8.52 mm
Case a 3 and 9 o'clock Straight Shaped
Direction of the date numbers Same as reading direction Partly turned
7 o'clock markers Present Absent
6 o'clock marker Rectangular Rounded off
Hour and minute hands Slimmer Thicker
Plus a little bit different hour markers - 3712 have slimmer ones.
The bracelets are quite diffent. The center parts of the bracelet of 3712 are more rounded and it looks like there is much more hand work in the bracelet of 3712. It also feels slimmer but I have not measured that (yet). Finally, screw are used in the bracelet of 3712. In my eyes the color of the dials is not identical.
Even there are a lot of differences between 3712 and 5712, they are still the same watch on the wrist.
I hope this answered your question.
Best, Kari