To further the enlightenment: In America, any small (a few bites), sweet baked good, shaped (perhaps very roughly) like a flattened disk, is a cookie. Any small, salty baked wafer is a cracker. The one exception is Graham crackers, which are somewhat sweet but not salty, and most closely resemble what Brits call a digestive biscuit. It is my understanding that these products are both called “biscuits” in Britain, or “sweet biscuits” and “savoury biscuits” if the distinction need be made.
American biscuits are only vaguely similar to scones. They’re generally lighter and puffier, and have (I think) a somewhat more savory flavor. One would never see raisins or other fruits in biscuits, and they’re often served as an accompiament to meals, formal or informal. One more rural American dish, typically a breakfast, is biscuits and gravy, which is exactly what the name says: Biscuits broken onto a plate, and then smothered in an extremely high-fat sausage gravy. Americans have scones as well, which are more or less the same as British scones, but seen much less often.
Pudding in America refers to a specific sort of dairy dessert not entirely unlike custard. It typically comes in chocolate, vanilla, butterscotch, or tapioca flavors. We also have plum pudding (served only at Christmas), bread pudding, and rice pudding, which I believe are originally British dishes, but one would never refer to such as just “pudding”. In Britain, pudding is a general term which can refer to any dessert. Or there’s “black pudding” and “white pudding”, which are not desserts at all, but two varieties of boiled sausage, but one would never refer to those as just “pudding”, either.
In America, jelly and jam are both fruit spreads such as one might spread on toast or scones. Strictly speaking, jam contains pieces of solid fruit, while jelly contains only fruit juice, but most Americans use the terms interchangeably (most often “jelly”). Orange spreads only are referred to as marmelade, and a spread made from apples is apple butter, but any other fruit spread would be called jelly or jam. The dessert made from flavored, sugared gelatin is generally called by the trade name Jell-o, or (rarely) by the generic term “gelatin”. In Britain, jelly refers to the gelatin dessert, and fruit spreads are jam.
Corn, to Americans, refers exclusively to the grain known in the rest of the world as maize, sweetcorn, or American corn. Americans reserve the term maize (alternately, Indian corn) for a particular type of American corn, which tends to have hard kernals in a variety of colors (brown, white, red, even blue). This variety of corn doesn’t make for very good eating (except perhaps as popcorn), but is often used as a decoration in the fall. For Brits, corn can refer to any grain.
Cornbread is a uniquely American foodstuff, which therefore has no British name. It’s a bread made with cornmeal, instead of flour. It may or may not be sweetened, depending on the part of the country. It has a very crumbly texture, and is often used to sop up gravy or other sauces. Corn muffins are the same thing, except baked in small round tins instead of rectangular loafs.
Any I’m missing?