QA (Quality Assurance) refers to a planned way to monitor the quality of the process that maintains the quality of the product. QA plays a vital role in each phase of SDLC.
While QC (Quality Control) finds defects in the product. The process set by QA follows by QC to meet the expectation. QC is termed as a tester who finds bugs. They mainly rely on test cases prepared by QA. We can call the QC subset of QA.