I’ve seen both varieties in my grocery store. Will substituting one for the other change a recipe’s flavor?
By law, both bittersweet and semisweet chocolates contain a minimum of 35% chocolate liquor. The difference between the two is the amount of sugar used; semisweet is indeed sweeter, and bittersweet is a little more bitter.
Using these chocolates interchangeably in a multiple-ingredient recipe like cake, cookies, or sauce, is unlikely to dramatically affect the outcome. However, if chocolate is the focal point of flavor, in truffles or chocolate chunk cookies for example, you need to chose the level of sweetness you desire.