That's because it's exactly the same watch bar the new display which they have shoehorned in and a couple of minor software updates.
Apparently, the real Watch 7 (with a bigger battery, better radio, and modern flat-edged design like the iPhone) was scuttled at the last minute due to production issues, so they have to ship an upgraded Watch 6 instead with the larger displays that were destined for the redesigned Watch 7.
Hence the stupid glass thickness increase and the mysterious "available later this Fall".
Good on them for scrambling to actually have something to ship, but in my view, a Watch 7 purchase would be the ultimate triumph of marketing over common sense.
Just buy (or keep) the 6 instead. Or better move, wait for the 7, err Watch 8.