There are different varieties even though invented in France. The original was supposed to be chopped cornishons, capers ,herbs parsley , chives and mayo . It was served over a celriac salad to which a dash of mustard was added. In Denmark they added catsup and served it with fish and french fried potatoes. In Belgium it ws served with fries no catsup. Then creole style with paprika added and pretty strong. One of those things that everyone customizes.
Take Russian Dressing, if you served the stuff we make to a real Russian they would think you crazy. Their version is sour cream, red caviar and some spices mixed. Same color as ours but quite different. Like real 1000 island has chopped hard cooked egg white in it as that is the islands floating around. Everything and every place has its own version.