Biscuits, dumplings and scones all contain some combination of flour, leavening (baking powder), fat (butter, lard), and liquid (milk, cream, buttermilk). The amounts and types of these ingredients, and the way the dough is handled account for the differences in taste and texture. Plus obviously fruit or cheese or anything else you care to add will make a difference.
Personally, I don't think that dumplings are noticeably more like biscuits than scones are. The frozen dumplings my MIL served a few days ago were just as heavy as any scone, certainly not like a nice light fresh biscuit. It's really all down to the ingredients and the execution.