FabR[Senior Patek Moderator]
26166
Like for any other model, a different reference number (meaning specifically the *first four* digits) normally corresponds to a substantial change in the watch that goes beyond the dial. The dial alone is indicated by the three digits after the dash.
For instance, the complete reference of the "teaser" model is 5189G-001, where "001" uniquely identifies that enamel dial (G of course stands for the metal of the case, grey gold).
Any other Rare Handcraft dial of this exact same model will be listed as 5189G-xyz (and the three digits "xyz" are often chosen at random by Patek! ;-) Year is entirely not a factor in the process
Cheers.