PEF (Product Environmental Footprint) is the generic European environmental assessment method. A PEFCR (Product Environmental Footprint Category Rules) is the framework specific to a product category; it details that category's rules (functional unit, scope, allocations, assumptions by stage). PEF without a PEFCR leaves the practitioner too much freedom to allow public comparison. The European Commission maintains the official list of published PEFCRs.
Read the source article: Which method should you use to calculate a DPP (footprint, PEF, LCA)?