When people I know say bread, they usually mean a loaf that
can be sliced. A roll is considered as something you eat
w/ dinner, preferably warm and buttered. Rolls are usually
made w/ yeast. We also eat biscuits, w/ any meal but
esp. breakfast. These are made from a yeastless dough that is rolled out and cut into circles.
The name sweet roll speaks for itself. Not very many people
here use the term sweet buns, though I have heard the name
cinnamon buns. If we just say, "pass the buns", that is
generally understood to be a pre-packaged, pre-sliced kind
of roll intended for making sandwiches (ex. hamburger bun).