QC：Quality Control is the floorboard of the relevant personnel involved in product quality inspection, finding quality problem analysis, improvement and control of nonconforming product. Including IQC（Incoming Quality Control）, IPQC（In-Process Quality Control）, FQC（Final Quality Control）, OQC（Out-going Quality Control）, the range of general is called QC.
QA：Quality Assurance is through the establishing and maintaining a quality management system to ensure that product quality is no problem. Generally it includes system engineer, SQE（Supplier Quality Engineer）, CTS（Customer Technique Service ）, 6sigma engineer, measuring instruments checking and management personnel.
QA should not only know the problem and also should know these problem solution how to establish the solution, how to prevent in the futute. What only QC to do is just control the problem when it occurs but not necessarily to know why it should be controlled in this way. Greenutra Resource thinks their relationship in the parables of police and judge. QC is the police and QA is the judge. What police QC to do is to catch the violation of the law and can’t prevent other crime and to give others finally convicted. And what judge QA to do is to make laws prevent crime, according to legal sentence disposal results. That is to say, QC is mainly given priority to the ex post facto quality inspection class activities and the default error is allowed, expect to find and select error. QA is mainly prior quality assurance class activities to prevention; expect to reduce the error probability.