What is the difference between Quality Control and Quality Assurance?

Quality Control (QC) and Quality Assurance (QA) are complementary but distinct functions. QC involves testing products and processes to verify they meet specifications - reactive, focused on detecting defects. Activities include: analytical testing of raw materials, in-process samples, and final products; stability testing; release testing; and environmental monitoring. QA is a proactive system ensuring quality is built into processes. Activities include: developing SOPs and specifications; training programs; audit programs; deviation handling; change control; validation master plans; and regulatory submissions. QA sets the standards, QC verifies compliance. Together they form the quality management system required by GMP. QA is preventive (process-focused), while QC is detective (product-focused).