QA aims to prevent defects with a focus on the process used to make the product. It is a proactive quality process.
QC aims to identify (and correct) defects in the finished products. Quality control, therefore. Is a reactive process.
The goal of QA is to improve development and test processes so that defects do not arise when the product is being developed.
The goal of QC is to identify defects after a product is developed and before it’s released.
QA Establish a good quality management system and the assessment of its adequacy. Periodic conformance audits of the operations of the system.
QC Finding & eliminating sources of quality problems through tools & equipment so that customer’s equipment are continually met.
QA Prevention of quality problems through planned and systematic activities including documentation.
QC The activities of techniques used to achieve and maintain the product quality, process and service.
QA Everyone on the team involved in developing the product is responsible for quality assurance
QC Quality control is usually the responsibility of a specific team that tests the product for defects.
Verification is an example of QA
Validation/software testing is an example of QC
Statistical tools & techniques can be applied in both QA/QC when they are applied to processes (process inputs & operational parameters), they are called Statistical process control (SPC); & it becomes the part of QA.
When statistical tools & techniques are applied to finished products (process outputs), they are called as Statistical quality control (SQC) & comes under QC.
As a tool
QA is a managerial tool
QC is corrective tool
QA is process oriented
QC is product oriented