Spearmint has a sharper flavor and more intense aroma, while peppermint tends to be more delicate and sweet Do you find this true? I don't. I find peppermint much stronger than spearmint. Spearmint might be sharper, but peppermint is still not "more delicate" to me. And I wouldn't find them interchangeable at all, at least in a recipe that calls for one or another.