What is the difference between quality control and quality assurance?

Quality Assurance (QA) is proactive - systematic processes to ensure quality will be achieved, including procedures, training, audits, and planning. Quality Control (QC) is reactive - inspection and testing to verify work meets specifications. QA prevents defects; QC detects defects. Both are essential: QA establishes standards and procedures, while QC verifies compliance through inspections, material testing, and documentation. Together they form the quality management system ensuring project meets requirements.