POSITIVE DISPLACEMENT Pump
PDPs displace a fixed amount of liquid from suction side to discharge side. These pumps give very high pressures but little flow rates. So they are used in fluid power applications to pump oil in heavy duty machines (cranes, excavators, etc.).
Dynamic Head Pumps (DHP)
DHPs increase the kinetic energy of the flow which is then converted to pressure. These pumps give very large quantities at low pressures. So they are used in liquid transportation to pump e.g. to pump water from treatment stations to homes.