What is the diference between quality assurance and quality control?

Quality assurance generally stands for the process/department in charge with Quality control. It is a broader term to describe the end-to-end process - it deals with the setting up the controls (e.g. responsible staff, trainning etc) and managing the proper functioning of the whole process/QA system. Quality control is more used as an operational term - i.e. performing the controlling tasks. But people tend to use both terms interchangeably so unless you need to work out a sciencific theoretical piece of work you shoul not be so much concerned with the difference - anyone would understand what you are talking about.