[offrdmania]

An 18038 and 18238 all had hollow gold links. The solid links came much much later.

An 18038 and 18238 are essentially the same watch on the outside and use a the same mid-case parts. Dials between the two are interchangeable.

The difference is the movement. As said above, the 18038 is a single quick set complication and the 18238 is a double. An 18038 will be much more affordable though, by about 30%.