Elderflower syrup and elderberry liqueur are quite different in taste, but you might be able to substitute 1 for the other, depending on the recipe. Here's what you should know: 1. Flavor: Elderflower syrup is made from the blossoms of the elder tree and has a light, floral, and somewhat musky flavor. Elderberry liqueur, on the other hand, is made from the berries of the elder tree and has a richer, fruitier, and slightly tart taste. They don't taste the same, but both have unique and delightful flavors. 2. Alcohol Content: Elderflower syrup is non-alcoholic, while elderberry liqueur contains alcohol. If the alcohol content is important to the recipe, this could be a significant difference. 3. Substitution: If you're making a cocktail, you could substitute elderflower syrup for elderberry liqueur, but it will change the drink's flavor. You might also need to adjust other ingredients to balance the sweetness, as the syrup might be sweeter than the liqueur. For cooking or baking, the substitution should work in most cases. If you're looking for an alcoholic substitute with a similar flavor to elderberry liqueur, elderflower liqueur (like St-Germain) could be a better choice than elderflower syrup, although it will still have a more floral and less fruity flavor.