BETTY: Consists of alternating layers of fruit, usually apples, and buttered cake or cookie crumbs. Usually topped with extra crumbs on top that get browned when baked.
According to the Oxford Companion to Food, Betty probably refers to the name of the woman who prepared it.
BUCKLE: Usually a single-layer cake with fruit folded into the batter before it is baked, or sometimes the fruit is layered on top of the cake and that is covered with a crumb topping. These cakes have a tendency to fall or "buckle" due to the weight of the topping.
COBBLER: A deep dish dessert consisting of fruit topped with a biscuit crust and lightly sprinkled with sugar. The biscuit topping resembles cobblestones, thus "cobbler".
CRISP: Fruit covered with a mixture of butter, sugar, flour and sometimes nuts. "Crisp" denotes the crispy top this dessert gets when it bakes.
CRUMBLE: Similar to a crisp with a crumbly topping that includes oatmeal.
GRUNT: Much like a cobbler, except a grunt is made with berries and has a soft top due to the fact that it is steamed on top of the stove rather than baked in the oven. The fruit can often make sort of grunting sound as it cooks.
PANDOWDY: Baked in the oven, fruit, usually apples, with a rich biscuit, cake or pastry crust. I'm told dowdying is the process of breaking up the crust topping and pushing it back into the fruit underneath, just before it is finished cooking.