This may or may not belong on this board, but this is a start. Just spent a week in Palm Springs area visiting relatives. Two pretty standard products turned out to be quite different in California and the Midwest (Chicago, in my case). One was Hellman's mayonnaise (here), something different in Ca--sorry, have forgotten Ca name--but retailer or distributer (I forget which) insisted it's the same product, just labelled differently "west of the Rockies". I don't know about that, but in fact much prefer the Ca version--brighter flavor, fluffier (clearly whipped), less fat-heavy. The other instance was more curious. Same name, same brand--French's mustard. Here it's yellow, salty, vinegary, with mild mustard flavor, and that's it. The Ca version is all the above, but in addition has a little heat--sort of like Dijon.
Anyone with transcontinental experience run into other products like this?