In software engineering, testing plays a vital phase and in many occasion we use Quality Assurance (QA) and Quality Control (QC) interchangeably. and I was getting it wrong until today (while attending in a session conducted by Pankaj Rabra) to know that testing is a part of QC not QA!
QC is about the product. To check if the product meets the requirements or not. It includes reviewing the requirements, code, design.
QA is about the process through which the product is going to built. Is the team following a right process in all development life-cycle.