In the previous post I mentioned the different models. In the Sahara color I have the 3 models together. In these pictures you can see the differences.
The earliest model (< 1961), is the tallest phone with its 23 cm. The other 2 are about 2 cm smaller.
The next difference you can see is the ear-piece. In the left picture it is shown that the angle changed after redesigning the original phone to a smaller type. This was the reason to reshape the ear-piece and make the angle close to its original value in the right picture.
These are the differences that you can see on the shell from the outside. There are other differences if you dive deeper in the phones.