Quality assurance (QA) and quality control (QC) are two related but distinct concepts that are used to ensure that a product or service meets certain standards of quality. The main difference between QA and QC is that QA focuses on preventing defects from occurring, while QC focuses on identifying and correcting defects after they occur.

Quality assurance involves the processes and procedures that are put in place to ensure that a product or service meets the desired level of quality. This includes things like setting quality standards, creating procedures for testing and inspection, and ensuring that the people involved in the production process are properly trained and equipped to do their jobs effectively.

On the other hand, quality control involves the activities that are undertaken to detect and correct defects in a product or service. This includes things like inspections, testing, and audits to identify defects, as well as taking corrective action to address any issues that are found.

In short, QA is about preventing quality problems from happening in the first place, while QC is about identifying and fixing quality problems after they have occurred. Both are important parts of the quality management process, and together they help to ensure that products and services meet the desired level of quality.