Salad dressings can be perplexing, with a wide assortment on store shelves and restaurant tables. Sometimes the differences between two of them can be so granular that it’s not clear what you should be ordering.

Case in point? Thousand Island vs. Russian dressing. Both are vaguely pink and chunky, and both taste similar. So which is which?

According to Eater, the two have at least two things in common. Both are made with a somewhat alarming combination of ketchup and mayonnaise, and both typically contain pickle relish.

The two go their separate ways when it comes to other ingredients. Russian dressing’s flavor comes mainly from the addition of horseradish. It also adds Worcestershire sauce, lemon juice, paprika, and onion powder. You were once likely to encounter Russian on a Reuben sandwich, which combines corned beef, Swiss cheese, and sauerkraut. Because of the horseradish, it’s also the dressing most likely to clear your sinuses thanks to a compound called allyl isothiocyanate, a nose-running component. Consider it the spicier of the two.

Russian dressing was invented by James E. Colburn in New Hampshire circa the early 1900s. Originally, Russian dressing got its pink tint from poached coral and pulverized lobster shell. The name doesn’t have a definitive origin, though it’s possible it came from a belief that Russians enjoy pickles and ethnic stereotyping has long been a thing in the food world.

Thousand Island adds chopped ingredients like a boiled egg, onions, and olives. You might also get some parsley tossed in there. Thousand Island is pretty close to the sauce you get on Big Macs at McDonald’s and animal-style burgers at In-N-Out. It’s likely the presence of Russian dressing on the Reuben that gave fast food proprietors the idea for a tangy dressing on their menu items. It was most likely invented by Sophia LaLonde and named for the Thousand Islands region between northern New York and southern Ontario, Canada.

Per Eater, Russian dressing might be getting phased out—at least the name is. Whether people use one recipe or another, they tend to dub it Thousand Island to avoid confusion. However, you can still find dressing labeled Russian on store shelves. One from Wish-Bone boasts of a “sweet tomato, tangy vinegar” flavor and has a dark red appearance, while their Thousand Island is the more familiar pink and highlights the pickle relish. Grab whichever one you like, but on sandwiches and salads, Thousand Island appears to be the victor.

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This article was originally published on www.mentalfloss.com as Thousand Island vs. Russian Dressing: What’s the Difference?.