The terms performance, competence and capability all denote different things and need to be used appropriately to ensure clarity of meaning
People often use these three terms interchangeably. However, in practical terms, performance is action,and competence and capability are attributes.
Consistently poor performance might be caused by a lack of competence or a lack of capability (see below).
Erratic performance is more likely to be caused by other factors, such as personal difficulties or intermittent health issues.
Competence is evidenced by performance that is consistently of a required standard. Professionals must maintain their competence and can do this by undertaking continuing professional development.
Capability is a term used in employment law. A person with capability for the work in question can become competent with the appropriate support, training, development and/or experience. If, for whatever reason, the person does not have the capability, these interventions won’t result in them becoming competent.
Capability becomes competence when performance is consistently of the required standard.