The terms “quality assurance” and “quality control” are often used interchangeably to refer to ways of ensuring the quality of a service or product. The terms, however, have different meanings.

• Assurance: The act of giving confidence, the state of being certain or the act of making certain.
  Quality assurance: The planned and systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled.

• Control: An evaluation to indicate needed corrective responses; the act of guiding a process in which variability is attributable to a constant system of chance causes.
  Quality control: The observation techniques and activities used to fulfill requirements for quality.