Accreditation is used to recognize the technical and organizational competence of a conformity assessment body. Certification validates compliance with established requirements.
Accreditation = Confirmation and recognition of technical competence
Confirmation by a third party, formally recognizing that a conformity assessment body has the competence to execute specific conformity assessment tasks (according to ISO/CEI 17000, 5.6).
Certification = Confirmation of compliance with established requirements
Procedure according to which a third party confirms in writing that products, processes, systems or persons comply with established requirements (see also ISO/CEI 17000, 5.5). Certification is one of the various types of conformity assessment.
Admittedly, the two activities present certain similarities, but they can be differentiated as follows: accreditation focuses its action on formal recognition of competence, which requires in-depth technical knowledge, and therefore, recourse to an expert for each accredited sector. The purpose of certification is, above all, to attest that an activity complies with a norm or standards.
Source: Swiss Accreditation Service SAS, last changed: 06/29/2016