Here are things that I understand about the difference in QA and QC. 

QA is process-oriented, aiming to build quality into the product from the start, whereas QC is product-oriented, ensuring the finished product meets the required standards.

QA takes place during the design and development stages, while QC happens after or during production.

The goal of QA is to prevent defects, while QC focuses on identifying and correcting them.

QA relies on audits, process reviews, and regulatory checks, whereas QC uses testing, inspections, and statistical analysis.

QA and QC often work together, even in the same departments. QA established the baseline requirements, and even makes a lot of the SOP's. QC does many of the stability tests, and statistical analysis to make sure products and procedures are in conformance. Although there is that distinction, the tasks also often overlapped between roles. 

Quality Control often works with production, and some have Quality Inspector in their title. Their training is often related to procedures in their position related to Non-Conformance Reports and CAPA. The QA personnel need training to get a better systems based understanding of a company's QMS. 

QA and QC do overlap because they both focus on product quality, but the skill sets and career pathways can be quite distinct. QA is primarily about systems and processes—it ensures that the proper procedures are in place and that the organization complies with legislation. This often includes regulatory standards training (such as ISO 13485, FDA rules, or GMP) and auditing, documentation, and risk management abilities. QA positions may include quality systems manager, regulatory compliance professional, or internal auditor. In contrast, quality control is more hands-on with the product. Training is typically more technical, such as performing experiments, utilizing lab equipment, analyzing data, or implementing statistical process control. QC positions may include lab technician, inspection specialist, or product testing engineer. I believe going from QC to QA is more challenging than the reverse. Someone in QC often has good technical testing abilities, whereas QA need a more comprehensive grasp of rules and process design. On the other hand, a QA professional who has been exposed to testing methodologies may find it easier to transition into QC since they will already understand why such tests are important. So, in my perspective, switching is doable, but it generally relies on whether someone sought cross-training or experience outside of their primary function.

Quality Assurance (QA) uses preventive systems and processes to stop errors before they occur but Quality Control (QC) verifies finished products against established standards. The core distinction between QA and QC training emerges from their educational material because QA teaches us about regulatory frameworks and documentation systems and auditing procedures whereas QC provides hands-on training for testing and inspection work and laboratory operations. The QA roles consist of QA Specialist and Compliance Officer positions yet QC roles consist of QC Analyst and Lab Technician positions. The shift from QC to QA proves more difficult because QA requires knowledge of regulatory compliance and documentation standards yet the transition from QA to QC becomes easier because QA professionals already understand standards but need to learn technical testing skills. The main distinction between QA and QC exists in their operational methods because QA works preventively across entire systems yet QC focuses on product quality through reactive methods.

Quality Assurance is about building processes to prevent any issues with the product is process oriented. Quality Control is about identifying issues with the product and is product oriented. Quality Assurance is preventative in nature while Quality Control is more reactive in nature. You can expect quality engineers to work in Quality Assurance since they can create processes and oversee audits. You can expect quality technicians to work in Quality Control since they inspect the product and identify issues with the product. Switching from QC to QA is harder because while you may be able to identify issues with the product, you need a higher level of understanding to prevent those issues from happening. QA to QC is easier because you already have the knowledge of understanding how to prevent issues from happening and you can apply that to identifying issues with the product. So between the two, Quality Assurance requires a higher level of understanding because you need to be able to identify the problem and identify ways to prevent that problem from happening.

QA focuses on processes (about building systems and procedures to prevent defects before they happen). QC, on the other hand, focuses on products and is about identifying and correcting defects through inspection and testing. QA professionals usually need a strong understanding of regulatory standards (like ISO 13485 or FDA 21 CFR Part 820 in medical devices), risk management, and process validation. QC specialists are typically trained in laboratory techniques, statistical sampling, equipment calibration, and test methods. QA jobs often include titles such as Quality Systems Engineer, Compliance Specialist, or Validation Engineer, while QC roles might include Quality Inspector, Lab Technician, or Test Engineer. Moving from QA to QC is typically easier technically but can feel like a step backward in responsibility or scope.