Usuful link about QA vs QC

Quality assurance and quality control represents a two elements of quality management. 

Even are quality assurance and quality control activities are linked, still they are defined differently. Typically, QA activities and responsibilities cover virtually all of the quality system, while QC is a subset of the QA activities. 

Sometimes, elements in the quality system might not be specifically covered by QA/QC activities and responsibilities but again may involve QA and QC.                                                    

                                                                         Quality System, Quality Assurance, and Quality Control Relationships

Fig.: Quality system, Quality Assurance and Quality Control Relationship; Source: Quality Assurance vs Quality Control: Definitions & Differences | ASQ