Quality Control controls the quality of the product to ensure customer requirements and needs are meet and Quality Assurance assures that quality requirements will be meet based on customers, FDA, regulations, certifiers and 3rd parties. QA and QC works together and establish quality guidelines and objectives that act as guidance for an organizational procedures and policies. For the most part there’s always good relations between quality control and quality assurance departments. I have seen sometimes that QA implements new changes based on new regulations and if QC is not prepared to implement those changes, issue arise delaying the process. Usually these are temporary obstacles and can be resolved with better communication.