Q: What is the difference between blanching and parboiling?
A: There's very small difference really. Blanching refers to the process of quickly dipping an item into boiling water and then quickly chilling it by then plunging it into ice water. It's a method used to make skins easier to remove, to reduce strong odors or to set the color of vegetables. Parboiling includes the quick boiling part, but not the chilling part. Parboiling is usually used to precook an item which will then be cooked another way such as braising, grilling or stir-frying.
Q: Are dark and light brown sugar interchangeable in cooking?
A: Yes, usually. Keep in mind the darker the sugar, the more intense the molasses flavor. The dark brown sugar will also burn more quickly, because of the more concentrated molasses. When long cooking times are required, in baking beans, for instance, if you use the darker sugar you may end up burning the beans. When only brown sugar is specified in a recipe, usually light brown sugar is what the author had in mind.