what is difference between QA ,QC and test engineer

Quality Assurance: set of activities designed to ensure that teh development and maintenance process is adequate to ensure a system will meets its objectives. (making sure customer is satisfired)

Quality Control: set activities designed to ealuate a developed work product. these activities can always include teh audits conducted by teh QA team to assess the cost of correcting defects, documentation. (making sure quality is good enough to go to market, basically we are evaluating the software)

TEsting: finding defect by executing a system/software. (process of executing a system" includes test planning prior to teh execution of teh test cases.