The terms "quality control" and "quality assurance" are not synonymous. There is a distinct difference between them both in meaning and purpose. While quality assurance is meant to prevent problems, quality control detects any problems that occur. Each one requires different skills, and separate departments in an organization are responsible for each aspect of the quality guarantee. Internationally recognized standards for both procedures come under the International Organization for Standardization (regulation ISO 9001:2008).
Quality assurance describes a process. The role of a quality assurance department is to devise procedures and systems in collaboration with other departments that ensure all deliverables are constantly of good quality. The deliverables may be factory-produced goods or a service; for example, quality assurance plays an important role in health services. Following the quality assurance process should guarantee that goods and services are flawless, and reduce management and employee time spent investigating complaints and reorganizing systems. Quality assurance is proactive in that it aims to prevent defects or problems from occurring. Management and third-party auditors are usually responsible for establishing quality assurance standards, checklists, relevant documentation and audits of internal processes.
Quality control describes a product-based approach rather than a process. In a product life cycle, it comes after the product is made and before it is delivered to customers. The quality control department checks that items conform to specific standards. If changes are necessary, the quality control personnel state what is needed. Compared with quality assurance, quality control is reactive, or corrective, in that it exists to identify defects and correct them. Quality control is usually devised and supervised by engineers and inspectors, particularly in a manufacturing environment.
One of the reasons for confusing quality assurance and quality control is that they are largely interdependent. The quality assurance department relies on feedback from quality control to identify areas where the preventive process needs changes. For example, the the quality assurance department may investigate the causes of defects as reported by quality control, and subsequently establish a new procedure to prevent them from happening again. After the new procedures are established, the quality control department checks that the goods meet the new quality standards. In some organizations, particularly service-oriented ones, it may be more difficult to tell the difference between the two functions, and in fact, the same department may be responsible for both quality assurance and quality control.