Effectively, certification is the third-party confirmation via audit of an organisation's systems or products, whilst accreditation is independent third-party recognition that an organisation has the competence and impartiality to perform specific technical activities such as certification, testing and inspection.
Just as end user organisations have to demonstrate their conformity with a set of criteria to a certification body in order to be certified, in turn certification bodies have to demonstrate their competence, impartiality and integrity to accreditation body in order to be accredited. In other words, if certification bodies are 'the checkers' then AB's role as the government-appointed National Accreditation Body is to 'check the checkers'.
It follows that only certification bodies can refer to themselves as 'accredited', whereas the organisations successfully audited by certification bodies hold 'certification'. If the certification body has been accredited by accreditation body to audit that particular activity, then organisations successfully audited by that certification body hold 'accredited certification'.
Accreditation involves the assessment of the competence and impartiality of an organisation and the compliance of their work to nationally and internationally recognised standards or schemes, such as the ISO 17021 certification body standard.
Accreditation is very specific to the activities it covers under the relevant standard; for example just because a laboratory is accredited for testing saliva swab samples for the presence of COVID-19 antigens, it does not necessarily mean it is also accredited for testing either other samples for COVID-19 antigens and/or saliva swabs for any other antigens.
The scope of the specific activities covered by accreditation are listed on the organisation's schedule of accreditation.
Whilst the terms ‘certification’ and ‘accreditation’ are often used interchangeably, they are two closely related but distinct steps on the quality assurance ladder.
Certification is an audit of whether an organisation, product or individual, conforms to the criteria laid out in a recognised standard or scheme, such as ISO 9001 Quality Management Systems.
Accreditation is a rung further up the ladder, performing an oversight role that underpins the quality, impartiality and competence of the certification process.