What is the basic difference between the Pressure equipment directive and the pressure equipment safety regulations?

The pressure Equipment Directive is a European Directive intended for all member states of the EU. European directives are extremely difficult to police and enforce, so they are simply a directive which the respective governments must adhere to. It was initially intended to ensure a common standard of manufacturing safety and workmanship control, by stipulating design documentation, testing, material control and traceability, and inspection requirements during construction and fabrication of pressure equipment. By doing so, the standard and safety of pressure equipment across the boundaries of EU states, became more uniform, hence it resulted in a virtual removal of trade barriers. The Pressure Equipment Regulations are a means of an individual state (in this case UK) of legally enforcing the requirements of the PED.