the picture on the left looks like the downstream and the rock auto picture is the upstream. look on rockauto and all the upstream o2 sensors look like the denso one.
Actually, picture on the left looks more like upstream -but without California emissions. My installed downstream is OK and consistent with the one on rockauto (right image). Also, there are 6 pins on upstream and 4 pins on downstream. So, it is unlikely that I have downstream installed on my upstream location.
Probably, they put a federal emission sensor instead of a California emission sensor. But I never got an error code about that. My average mileage is very low by the way.
Save your paperwork proving the part you installed is Calif compliant. The Calif emissions testing techs usually do a visual inspection of the O2 sensors. BTW, if in doubt it would be a good idea show this info to one of those Calif emissions testing techs for advice.