The first edition (that should be 2005) does not include the Jeweller tile. This building was originally a promo they gave out at Essen. In all later editions this tile is included.
Regarding the Jeweller tile, so far I have played about 9 games of Caylus and the Jeweller was built once, or twice. So it is not the most important tile, but it gets used.
The rules of all editions are the same. The graphics were updated in later editions.
another difference, in the original versions the Lawyer building was worth 4 points, however, somewhere in the newer releases the Lawyer changed to be worth only 3 points when built. I don't think this has any effect on game play and can't imagine why they changed it.