The 1601 is an earlier model DateJust than the 16030.
The movement in the 1601 is a calibre: 1575 and the 16030 is I believe a calibre: 3035.
The 1601 does not have a quickset date but the 16030 does.
The dial on the 1601 is called a 'piepan' dial as it has a 1-2mm beveled edge on the dial. On the other hand the 16030 has no edge and the surface of the dial is uniform around the edge (perimeter).
Both are 36mm wide cases and both have a plexiglass crystal.
I personally prefer the 1601
