Ref. 18038
Ref. 1803
These are two major versions of Day date, the former one with plastic crystal, and the later one with Sapphire. The former model Ref 1803 is thinner; the later version Ref 18038 is thicker. The former one is having a dial with a curved and truncated dial at the rim of it. Where 18038 is flat. As far as accuracy is concern, basically they are both the same under the same Rolex quality. As for my preference, I do not see any one is better than others. The 1803 is classic. Slimmer. Warmers and more isometric in the outlook due to the slant dial. The 18038 has a new caliber, more durable, scratches proof, big looks thicker. Less elegant. So I think I will wear new newer 18038 for work and 1803 for meeting my watch collectors during week end. Value, I think all depends on the dial, I like dial with diamond, as they are rarer, and the one with Purple dial is extremely rare… I love it. HK Snob