How is dump truck and tipper truck different?

Just different dialects, is all. Dump truck is more common in North America - specifically, the United States, whereas 'tipper' tends to be the more prevalent term in Commonwealth countries, Europe, etc. A dump truck in America is a tipper elsewhere, and vice versa, although the term dump truck is a bit more broad, and includes bottom dumps, whereas tipper tends to apply only to vehicles in which the dump bed actually does tip (either to the rear or to the side).