The answer is that they are similar, but not the same. The Government Product/Services Accessibility Template (GPAT) reflects the government agency's accessibility requirements for the type of EIT they intend to buy. The Voluntary Product Accessibility Template (VPAT) reflects the accessibility features of the vendor's product. Requirements may or may not match features. Features may or may not match requirements. The implication for an agency is that you have to assess all accessibility features of a product and not just those you have specified. The implication for a vendor is that you have to document all the accessibility features of your product and not just those identified by the agency.